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STATIOW'^EXT BOOK. 




SAMUEL W. JOHNSON, M. A. 



HOW CROPS GROW. 

A TREATISE ON THE \^^^C\ V^ 

r\ 

\ 1 

CHEMICAL COMPOSITION, STRUCTURE 
AND LIFE OF THE PLANT, 



FOE STUDENTS OF AGKICULTURE. 



WITH 



NUMEROUS ILLUSTRATIONS AND TABLES OF ANALYSES. 



■/' 



SAMUEL W^JOHNSON, M. A., 

II 
PROFEPROU OP TIIEOKETICAL AND AGRICULTUnAL CHEMISTRY IN THE SHEF- 
FIELD SCIENTIFIC SCHOOL OP YALE UNIVERSITY ; DIRECTOR OP 
THE CONNECTICUT AORICHLTURAL EXPERIMENT STATION; 
MEMBER OP THE NATIONAL ACADEMY OP SCIENCES. 



REVISED AXD ENLARGED EDITION. 



NEW YORK: 

ORANGE JUDD COMPANY, 

1898. 







Entered, according to Act of Congress, in tlie year 18'J0, by tlie 

ORANGE JUDD COMPANY, 

In the Office of the Librarian of Congress, at Wasliington. 



By uraAiiXdi 



JUN 13 1914 




PREFACE. 

— — :o: 

The original edition of this work, first published in 
1868, was the result of studies undertaken in preparing 
instruction in Agricultural Chemistry which the Author 
has now been giving for three and thirty years. To- 
gether with the companion volume, *^How Cro^^s Feed," 
it was intended to present concisely but fully the then 
present state of Science regarding the Nutrition of the 
higher Plants and the relations of the Atmosphere, 
Water, and the Soil, to Agricultural Vegetation. Since 
its first appearance, our knowledge of the subject treated 
of in the present volume has largely participated in the 
remarkable advances which have marked all branches of 
Science during the last twenty. year^. and it has been the 
writers' endeavor in this revised edition to post the book 
to date as fully as possible without greatly enlarging its 
bulk or changing its essential character. In attempting 
to reach this result he has been doubly embarassed, first, 
by the great and rapidly increasing amount of recent 
publications in which the materials for revision must be 
sought, and, second, by the fact that official duties have 
allowed very insufficient time for a careful and compre- 
hensive study of the literature. In conclusion, it is 
hoped that while the limits of the book make necessary 
the omission of a multitude of interesting details, little 
has been overlooked that is of real importance to a fair 
presentation of the subjects discussed. 
Ill 



TABLE OF CONTENTS. 



Introduction 1 

DIVISION I.— CHEMICAL COMPOSITION OF THE PLANT. 

Chap. I.— The Volatile Pakt of Plants 12 

§ 1. Distinctions and Definitions.. 12 

§ 2. Elements of the Volatile Part of Plants 14 

I 3. Chemical Affinity 29 

§ 4. Vegetable Organic Compounds or Proximate Elements 36 

1. Water 37 

2. Carbhydrates 39 

3. Vegetable Acids 75 

4. Fats 83 

5. Albuminoids and Ferments 87 

6. Amides 114 

7. Allvaloids 120 

8. Phosphorized Substances 122 

Chap. II.— The Ash of Plants 126 

§ 1. Ingredients of the Ash 126 

Non-metallic Klenients 127 

Carbon and its Compounds 128 

Sulphur and its Compounds. 129 

Phospliorus and its Compounds 132 

Chlorine and its Compounds 132 

Silicon and its Comijounds 134 

Metallic Kleiiients . . 138 

Potassium and its Comi^ounds 138 

Sodium and its Compounds 139 

Calcium and its Compounds 139 

Magnesium and its Compounds 140 

Iron and its Coniijounds 141 

Manganese and its Compounds 142 

Salts 143 

Carbonates 144 

Sulphates , 146 

Phospliates 147 

Chlorides 149 

Nitrates 149 

§ 2. Quantity, Distribution, and Variations of the Ash 151 

Table of Proportions of Ash in Vegetable Matter. . . .152 

§ 3. Special Composition of the Ash of Agricultural Plants 161 

1. Constant Ingredients 161 

2. Uniform comi3osition of normal specimens of 

given plants IGl 

Table of Ash-analyses 1G4 

3. Composition of Different parts of Plant 171 

4. Like coniposition of similar plants 173 

5. Variability of ash of same species 174 

6. Wliat is normal composition of the ash of a plant? 177 

7. To what extent is each ash-ingredient essential 

or accidental , 180 

Water-culture 180 

Essential ash-ingredients 18G 

Is Sodium Essential to Agricultural Plants ? 186 

Iron indisi)ensable 192 

Manganese unessential 1)3 

Is Chlorine indispensable ? li)4 

Silica is not essential 197 

Ash-ingredients taken up in excess ..201 

Disposition of superfluous mattei's 203 

State of Ash-ingredients in plant 207 

S 4. Functions of the Ash-ingredients 210 

Chap. III.— § l. Quantitative Relations among the Ingredients of 

Plants 220 

§ 2. Composition of the jilant in successive stages of 

growth 222 

Comx)osition and Growth of the Oat Plant 223 

Y 



YI TABLE OF CONTEN'TS. 

DIVISION II.— THE STRUCTITRE OF THE PLANT AND OFFICES 
OF ITS ORGANS. 

Chap. I.— Generalities 241 

Organism, Organs 242 

Chap. II.— Primary Elements of Organic Structure . . .243 

§ 1. The Vegetable Cell 243 

<j 2. Vegetable Tissues 254 

Chap, hi.— veoetative Organs 256 

§ 1. The Rout 256 

Offices of Root 260 

Apparent Search for Food 263 

Contact of Roots with Soil 266 

Absorption by Root 26t) 

Soil Roots, Water Roots, Air Roots 273 

§ 2. The Stem 282 

Buds 283 

Layers, Tillering 286 

Root-stocks 287 

Tubers 288 

Structure of the Stem 289 

Endogenous Plants 290 

Exogenous Plants 296 

Sieve-cells : 303 

§ 3. Leaves 306 

Leaf Pores 309 

Exhalation of AVater Vapor 311 

Offices of Foliage 314 

Chap. IV.— Reproductive Organs 315 

§ 1. The Flower 316 

Fertilizati on 319 

Hybridizing 324 

Species. Varieties 326 

§ 2. Fruit 330 

Seed .' 332 

Embryo 333 

§ 3. Vitality of seeds and their influence on the Plants 

they produce 335 

Duration of Vitality 335 

Use of old and unripe seeds 338 

Density of seeds 339 

Absolute weight of seeds 340 

Signs of Excellence 345 

Ancestry. Race-vigor 346 

DIVISION III.— LIFE OF THE PLANT. 
Chap, l.— Germination ,349 

§ 1. Introductory 349 

I 2. Plienomena of Germination 3,^0 

§ 3. Conditions of Germination 351 

Proper Dej^th of Sowing 355 

§ 4. Chemical Physiology of Germination 357 

Chemistry of Malt 358 

CilAP. II.— § 1. Food of the Plant when independent of the Seed.... 366 

§ 2. The Juices of the Plant. Their Nature and Movements369 

Flow of Sap 370 

Composition of Sap 376 

Kinds of Sap. 378 

Motion of N utrient Matters 379 

§ 3. Causes of Motion of the Juices 385 

Porosity of Tissues 385 

Imbibition 386 

Liquid Diffusion .'."..'.','..'.' .390 

Osmose or Membrane Diffusion '.'....'..... 393 

Root Action 399 

Selective Power of Plant .'......'. AOl 

§ 4. Mechanical effects of Osmose .406 

APPENDIX. 
Table.— Composition of Agricultural Products 409 



HOW CROPS GROW. 



INTRODUCTION. 



The object of agriculture is the production of certain 
plants and certain animals which are employed to feed, 
clothe and otherwise serve 'the human race. The first 
aim, in all cases, is the production of plants. 

Nature has made the most extensive provision for the 
spontaneous growth of an immense variety of vegetation ; 
but in those climates where civilization most certainly 
attains its fullest development, man is obliged to employ 
art to provide himself with the kinds and quantities of 
vegetable produce which his necessities or luxuries de- 
mand. In this defect, or, rather, neglect of nature, ag- 
riculture has its origin. 

The art of agriculture consists in certain practices and 
operations which have gradually grown out of an obser- 
vation and imitation of the best efforts of nature, or have 
been hit upon accidentally, or, finally, have been deduced 
from theory. 

The science of agriculture is the rational theory and 
systematic exposition of the successful art. 

Strictly considered, the art and science of agriculture 
are of equal age, and have grown together from the ear- 



2 HOW CROPS GROW. 

liest times. Those who first cultivated the soil by dig- 
ging, planting, manuring and irrigating, had their suffi- 
cient reason for every step. In ail cases, thought goes 
before work, and the intelligent workman always has a 
theory upon which his practice is planned. No farm 
was ever conducted without physiology, chemistry, and 
physics, any more than an aqueduct or a railway was ever 
built without mathematics and mechanics. Every suc- 
cessful farmer is, to some extent, a scientific man. Let 
him throw away the knowledge of facts and the knowl- 
edge of principles which constitute his science, and he 
has lost the elements of his success. The farmer without 
his reasons, his theory, his science, can have no plan ; 
and these wanting, agriculture would be as complete a 
failure with liim as it would be with a man of mere 
science, destitute of manual, financial and executive skill. 

Other qualifications being equal, the more advanced 
and complete the theory of which the farmer is the mas- 
ter, the more successful must be his farming. The more 
he knows, the more he can do. Tlie more deeply, com- 
prehensively, and clearly he can think, the more econ- 
omically and advantageously can he work. 

That there is any opposition or conflict between science 
and art, between theory and practice, is a delusive error. 
They are, as they ever have been and ever must be, in the 
fullest harmony. If they appear to jar or stand in con- 
tradiction, it is because we have something false or incom- 
plete in what we call our science or our art ; or else we do 
not perceive correctly, but are misled by the narrowness 
and aberrations of our vision. It is often said of a ma- 
chine, that it was good in theory, but failed in practice. 
Tins is as untrue as untrue can be. If a machine has 
failed in practice, it is because it v/as imperfect in theory. 
It should be said of such a failure — the machine was 
good, judged by the best theory known to its inventor, 
but its incapacity to work demonstrates that the theory 
had a flaw. 



INTRO DUCTIO IS". 3 

But, altbongh art and science are thus inseparable, it 
must not be forgotten that their growth is not altogether 
parallel. There are facts in art for which science can, as 
yet, furnish no adequate explauatioii. Art, though no 
older fchau science, grew at first more ra})idly in vigor 
and in stature. Agriculture was practiced hundreds and 
thousands of years ago, with a success that does not com- 
pare unfavorably with ours. Nearly all the essential 
points of modern cultivation were regarded by the Eo- 
mans before the Christian era. The annals of the Chi- 
nese show that their wonderful skill and knowledge were 
in use at a vastly earlier date. 

So much of science as can be attained through man's 
unaided senses, reached considerable perfection early in 
the world's history. But that part of science which re- 
lates to things invisible to the unassisted eye, could not 
be developed until the telescope and the microscope had 
been invented, until the increasing experience of man and 
his improved art had created and made cheap the other 
inventions by whose aid the mind can penetrate the veil 
of nature. Art, guided at first by a very crude and im- 
perfectly-developed science, has, within a comparatively 
recent period, multiplied those instruments and means of 
research whereby science has expanded to her present 
proportions. 

The progress of agriculture is the joint work of theory 
and practice. In many departments great advances have 
been made during the last hundred years ; especially is 
this true in all that relates to implements and machines, 
and to the improvement of domestic animals. It is, 
however, in just these departments that an improved 
theory has had sway. More recent is the development of 
agriculture in its chemical and physiological aspects. In 
these directions the present century, or we might almost 
say the last fifty years, has seen more accomplislied than 
all previous time. 



4 now CROPS GROW. 

The first book in the English language on the subjects 
which occupy a good part of tlie following pages, was 
written by a Scotch nobleman, the Earl of Dundonald, 
and was published at London in 1795. It is entitled: 
*^ A Treatise showing the Intimate Connection that sub- 
sists between Agriculture and Chemistry." The learned 
Earl, in his Introduction, remarked that ^Hhe slow pro- 
gress which agriculture has hitherto made as a science is 
to be ascribed to a want of education on the part of the 
cultivators of the soil, and the want of knowledge in such 
authors as have written on agriculture of the intimate 
connection that subsists between the science and that of 
chemistry. Indeed, there is no operation or process, not 
merely mechanical, that does not depend on chemistry, 
which is defined to be a knowledge of the properties of 
bodies, and of the effects resulting from their different 
combinations. " Earl Dundonald could not fail to see that 
chemistry was ere long to open a splendid future for the 
ancient art that always had been and always is to be the 
prime support of the nations. But when he wrote, how 
feeble was the light that chemistry could throw upon the 
fundamental questions of agricultural science ! The 
chemical nature of atmospheric air was then a discovery 
of barely twenty years' standing. The composition of 
water had been known but twelve years. The only ac- 
count of the composition of plants that Earl Dundonald 
could give was the following: *^ Vegetables consist of 
mucilaginous matter, resinous matter, matter analogous 
to that of animals, and some proportion of oil. * * 
Besides these, vegetables contain earthy matters, formerly 
held in solution in the newly-taken-in juices of the 
growing vegetable." He further explains by mentioning 
on subsequent pages that starch belongs to the mucil- 
aginous matters, and that, on analysis by fire, vegetables 
yield soluble alkaline salts and insoluble phosphate of 
lime. But these salts, he held, were formed in the pro- 



IKTRODUCTTOIT. 5 

cess of burning, their lime excepted, and the fact of their 
being taken from the soil and constituting the indispen- 
sable food of plants, his Lordship was unacquainted with. 
The gist of agricultural chemistry with him was, that 
plants are ** composed of gases with a small proportion of 
calcareous matter;" for '' although this discovery may 
appear to be of small moment to tlie practical farmer, yet 
it is well deserving of his attention and notice, as it 
throws great light on the nature and food of vegetables." 
The fact being then known that plants absorb carbonic 
acid from the air, and employ its carbon in their growth, 
the theory was held that fertilizers operate by promoting 
the conversion of the organic matter of the soil or of 
composts into gases, or into soluble humus, which were 
considered to be the food of plants. 

The first accurate analysis of a vegetable substance was 
not accomplished until fifteen years after the publication 
of Dimdonald's Treatise, and another like period passed 
before the means of rapidly multiplying good analyses 
had been worked out by Liebig. So late as 1838, the Got- 
tingen Academy offered a prize for a satisfactory solution 
of the then vexed question whether the ingredients of 
ashe=; are essential to vegetable growth. It is, in fact, 
during the last fifty years that agricultural chemistry has 
come to rest on sure foundations. Our knowleds^e of the 
structure and physiology of plants is of like recent devel- 
opment. AVhat immense practical benefit the farmer has 
gathered from this advance of science ! Chemistry has 
ascertained what vegetation absolutely demands for its 
growth, and points out a multitude of sources whence 
the requ'sibe materials for crops can be derived. Cato 
and Columella knew indeed that ashes, bones, bird- 
dung and green manuring, as well as drainage and aera- 
tion of the soil, were good for crops ; but that carbonic 
acid, potash, phosphate of lime, and compounds of nitro- 
gen are the chief pabulum of vegetation, they did not 



6 HOW CROPS GROW. 

know. They did not know that the atmosphere dissolves 
the rocks, and converts inert stone into nutritive soil. 
These grand principles, understood in many of their de- 
tails, are an inestimable boon to agriculture, and intelli^ 
gent farmers have not been slow to apply them in prac- 
tice. The vast trade in phosphatic and Peruvian guano, 
and in nitrate of soda ; the great manufactures of oil of 
vitriol, of superphosphate of lime, of fish fertilizers ; and 
the mining of fossil bones and of potash salts, are indus- 
tries largely or entirely based upon and controlled by 
chemistry in the service of agriculture. 

Every day is now tlie witness of new advances. The 
means of investigation, which, in the hands of the scien- 
tific experimenter, have created within the writer's mem- 
ory sucli arts as photography and electro-metallurgy, and 
have produced the steam-engine, the telegraph, the tele- 
phone and the electric light, are working and shall ever- 
more continue to work progress in the art of agriculture. 
This improvement will not consist so much in any re- 
markable discoveries that shall enable us to *'grow two 
blades of grass where but one grew before;" but in the 
oradual disclosure of the reasons of that which we have 
long known, or believed v/e knew; in the clear separa- 
tion of the true from the seemingly true, and in the ex- 
change of a wearying nncertainty for settled and positive 
knowledge. 

It is the boast of some who affect to glory in the suf- 
ficiency of practice and decry theory, that the former is 
based upon experience, v/hich is the only safe guide. But 
this is a one-sided view of the matter. Theory is also 
based upon experience, if it be worth the name. Tlie 
fancies of an ignorant and undisciplined mind are not 
theory as that term is properly understood. Theory, in 
the strict scientific sense, is always a deduction from 
facts, and the best deduction of which the stock of faces 
in our possession admits. It is therefore also the inter- 



INTRODUCTION". 7 

prdLiition of facts. It is tlio expression of tlio ideas wliicli 
facts awaken when submitted to a fertile imagination and 
well-balanced judgment. A scientific theory is intended 
for tlie nearest possible approach to the truth. Theory 
is confessedly imperfect, because our knowledge of facts 
is incomplete, our mental insight weak, and our judg- 
ment fallible. But the scientific theory which is framed 
by the contributions of a multitude of earnest thinkers 
and workers, among wliom are likely to be the most gifted 
intellects and most skillful hands, is, in these days, to a 
great extent worthy of the Divine truth in nature, of 
which it is the completest human conception and ex- 
pression. 

Science employs, in effecting its progress, essentially 
the same methods that are used by merely practical men. 
Its success is commonly more rapid and brilliant, because 
its instruments of observation are finer and more skill- 
fully handled ; because it experiments more industriously 
and variedly, thus commanding a wider and more fruit- 
ful experience ; because it usually brings a more culti- 
vated imagination and a more disciplined judgment to 
bear upon its work. The devotion of a life to discovery 
or invention is sure to yield greater results than a desul- 
tory apidication made in the intervals of other absorbing 
pursuits. It is then for the interest of the farmer to 
avail himself of the labors of the man of science, when 
the latter is willing to inform himself in the details of 
practice, so as rightly to comprehend the questions which 
press for a solution. 

Agricultural science, in its widest scope, comprehends 
a vast range of subjects. It includes something from 
nearly every department of human learning. The natu- 
ral sciences of geology, meteorology, mechanics, physics, 
chemistry, botany, zoology and physiology, are most in- 
timately related to it. It is not less concerned with so- 
cial and political economy. In this treatise it will not be 



8 HOW CROPS GROW. 

attempted to touch, much less cover, all this ground, but 
some account will be given of certain subjects whose un- 
derstanding will be of the most direct service to the agri- 
culturist. The Theory of Agriculture, as founded on 
chemical, physical and physiological science, in so far as 
it relates to the Chemical Composition, the Structure and 
the Life of the Plant, is the topic of this volume. 

Some preliminary propositions and definitions may be 
serviceable to the reader. 

Science deals with Matter and Force. 

Matter is that which has weight and bulk. 

Force is the cause of changes in matter — it is appre- 
ciable only by its effects upon matter. 

Force resides in and is insei3arable from matter. 

Force manifests itself in motion and change. 

All matter is perpetually animated by force — is there- 
fore never at rest. What we call rest in matter is simply 
motion too fine for our perceptions. 

The different kinds of matter known to science have 
been resolved into some seventy chemical elements or sim- 
ple substances. 

The elements of chemistry are forms of matter which 
have thus far resisted all attempts at their simplification 
or decomposition. 

In ordinary life we commonly encounter but twelve 
kinds of matter in their elementary state, viz. : 



Oxygen, 


Carbon, 


Mercury, 


Tin, 


Nitrogen, 


Iron, 


Copper, 


Silver, 


Sulphur, 


Zinc, 


Lead, 


Gold. 



The numberless other 'substances with which we are 
familiar, are mostly compounds of the above, or of twelve 
other elements, viz. : 

Hydrogen, Silicon, Calcium, Manganese, 

Phosphorus, Potassium, Magnesium, Chromium, 

Chlorine, Sodium, Aluminum, Nickel. 



INTRODUCTION". 



So far as human agency goes, these chemical elements 
are hidestructible as to quantity, and not convertible 
one into another. 

We distinguish various natural manifestations of force 
which, acting on or through matter, produce all material 
phenomena. In the subjoined scheme the recognized 
forces are to some extent chissified and defined, in a man- 
ner that may prove useful to the reader. 



Act at sensi- Tf^i^nioi^.o 

ble and in- I £Sct\vl 

sensible 1 ^tti active 

distances I Repulsive 



Act only at 
insensible 
distances 



Attractive 



LIGHT 
HEAT 

( ELECTRICITY 
) Magnetism 

r GRAVITATION 
COHESION 
Crystallization 
ADHESION 
Solution 
Osmose 
AFFINITY 
VITALITY 



[ Radiant 

> Inductive 
Cosmical 

Molecular 

Atomic 
Organic 



Physical 



Clieniical 
Biological 



Within human experience the different hinds of force 
are mostly convertible each into the others, and must 
therefore be regarded as fundamentally one and the same. 
Force, like matter, is indestructible. Force acting on 
a body may either increase its Kinetic Energy^ or be 
stored up in it as Potential Energy, Kinetic (or ac- 
tual) energy is the energy of a moving body. Potential 
(or possible) energy is the energy which a body may be 
able to exert because of its state or position. A falling 
stone or running clock gives out actual energy. The 
stone while being raised, or the clock w^liile winding, ac- 
quires and stores potential energy. In a similar manner 
kinetic solar energy, reaching the earth as light, heat and 
chemical force, rot only sets in operation the visible ac- 
tivities of plants, but accumulates in them a store of po- 
tential energy w^hich, when they serve as food or fuel, re- 
appears as kinetic energy in the forms of animal heat, 
muscular and nervous activity, or as fire and light. 

The sciences that more immediately relate to agricult- 
ure are Physics, Chemistry and Biology. 



10 HOW CROPS GROW. 

Physics, or ^'natural philosophy," is the science 
which considers the general properties of matter and such 
phenomena as are not accompanied hy essential change 
in its obvious qualities. All the forces in the preceding 
scheme, save the last two, manifest themselves through 
matter without destroying or masking the matter itself. 
Iron may be hot, luminous, or magnetic, may fall to the 
ground, be melted, welded, and crystallized ; but it re- 
mains iron, and is at once recognized as such. The forces 
whose play does not disturb the evident characters of sub- 
stances are physical. 

Chemistry is the science which studies the proper- 
ties peculiar to the various kinds of matter, and those 
phenomena which are accompanied by a fundamental 
change in the matter acted on. Iron rusts, wood burns, 
and both lose all the external characters that serve for 
their identification. They are, in fact, converted into 
other substances. Chemical attraction, affinity, or chem- 
ism, as it is variously termed, unites two or more ele- 
ments into compounds, unites compounds together into 
more complex compounds ; and, under the influence of 
heat, light, and other agencies, is annulled or overcome, 
so that compounds resolve themselves into simpler com- 
binations or into their elements. Chemistry is the science 
of composition and decomposition ; it considers the laws 
and results of affinity. 

Biology, or physiology, unfolds the laws of the 
prop:ig;ition, development, sustenance, and death of liv- 
ing organisms, both plants and animals. 

When we assert that the object of agriculture is to de- 
velop from the soil the greatest 2">ossible amount of cer- 
tain kinds of vegetable and animal produce at the least 
cost, we suggest the topics which are most important for 
the agriculturist to understand. 

The farmer deals with the plant, with the soil, with 
manures. These stand in close relation to each other, 



IKTEODUCTIOK. 11 

and to the atmosphere wliicli constantly surrounds and 
acts upon them. How the plant grows, — the conditions 
under which it flourishes or suffers detriment, — the ma- 
terials of which it is made, — the mode of its construction 
and organization, — how it feeds upon the soil and air, — 
how it serves as food to animals, — how the air, soil, 
plant, and animal stand related to each other in a per- 
petual round of the most beautiful and wonderful trans- 
formations, — these are some of the grand questions that 
come before us ; and they are not less interesting to the 
philosopher or man of culture, than important to the 
farniei" who dejiends upon their practical solution for his 
comfort ; or to the statesman, who regards them in their 
bearings upon the weightiest of political considerations. 



DIVISION 1. 

CHEMICAL COMPOSITION OF THE PLANT. 

CHAPTER 1. 
THE VOLATILE PART OF PLANTS. 

DISTINCTION'S AND DEFINITIONS. 

Organic and Inorganic Matter. —All matter may 
be divided into two great classes — Organic and Inorganic. 

Organic matter is the product of growth, or of vital 
organization, whether vegetable or animal. It is mostly 
combustible, i. e., it may be easily set on fire, and burns 
away into invisible gases. Organic matter either itself 
constitutes the organs of life and growth, and has a pecu- 
liarly organized structure, inimit.ible by art, — is made up 
of cells, tubes or fibres (wood and flesh) ; or else is a 
mere result or product of the vital processes, and desti- 
tute of this structure (sugar and fat). 

All matter which is not a part or product of a living 
organism is inorganic or mineral matter (rocks, soils, 
water, and air). Most of the naturally-occurring forms 
of inorganic matter which directly concern agricultural 
chemistry are incombustible, and destitute of anything 
like or2:anic structure. 

By the processes of combustion and decay, organic 
matter is disorganized or converted into inorganic matter, 
while, on the contrary, by vegetable growth inorganic 
matter is organized, and becomes organic. 
13 



1-i now CROPS GROW. 

Organic matters a-e in general characterized by com- 
plexity of constitution, and are exceedingly numerous 
and various ; while inorganic bodies are of simpler com- 
posi tion, and comparatively few in number. 

Volatile and Fixed Matter. — Ail plants and ani- 
mals, taken as a whole, and all of tlieir organs, consist of 
a volatile and fixed part, which may be separated by 
burning ; the former — usually by far the larger share — 
passing into and mingling with the air as invisible gases ; 
the latter — forming, in general, but from one to five per 
cent, of the whole — remaining as ashes. 

Experiment l.— A spUnter of wood heated in the flame of a lamp 
takes fire, burns, and yields volatile matter, which consvimes with liame, 
and ashes, which are the only visible residue of the combustion. 

Many organic bodies, products of life, but not essenti^il 
vital organs, as sugar, citric acid, etc., are completely 
volatile when in a state of purity, and leave no ash. 

Use of the Terms Organic and Inorganic. — It is 
usual among agricultural writers to confine the term or- 
ganic to the volatile or destructible portion of vegetable 
and animal bodies, and to designate their ash-ingredients 
as inort/cmic ^natter. This is not an entirely accurate 
distinction. What is found in the ashes of a tree or of a 
seed, in so far as it was an essontial part of the organism, 
was as truly organic as the volatile portion, and, by sub- 
mitting organic bodies to fire, they may be entirely con- 
verted into inorganic matter, the volatile as well as the 
fixed parts. 

Ultimate Elements that Constitute the Plant. — 
Chemistry has demonstrated that the volatile and de- 
structible part of organic bodies is chiefly made up of four 
substances, viz. : carbon, oxygen, hydrogen, and nitrogen, 
and contains two other elements in lesser quantity, viz. : 
sulphur and phosphorus. In the ash we may find phos- 
phorus, sulphur, silicon, chlorine, potassium, sodium, cal- 



THE VOLATILE PART OF PLANTS. 15 

cinm, magnesium, iron, and manganese, as well as oxy- 
gen, carbon, and nitrogen.* 

These fourteen bodies are elements, which means, in 
chemical language, that they cannot be resolved into 
other substances. All the varieties of vegetable and ani- 
mal matter are compounds, — are composed of and may be 
resolved into these elements. 

The above-named elements being essential to the or- 
ganism of every plant and animal, it is of the highest im- 
portance to make a minute study of their properties. 



2. 



ELEMENTS OF THE VOLATILE PART OF PLANTS. 

For the sake of convenience we shall first consider tlie 
elements which constitute the combustible part of plants, 
viz. : 

Carbon, Nitrogen, Sulphur, 

Oxygen, Hydrogen, Phosphorus. 

The elements which belong exclusively to the ash will 
be noticed in a subsequent chapter. 

Carbon, in the free state, is a solid. We are familiar 
with it in several forms, as lamp-bUick, charcoal, black- 
lead, and diamond. Notwithstanding the substances 
just named present great diversities of appearance and 
physical characters, they are identical in a certain chem- 
ical sense, as by burning they all yield the same product, 
viz. : carbonic acid gas, also called carbon dioxide. 

That carbon constitutes a large part of plants is evi- 
dent from the fact that it remains in a tolerably pure 
state after the incomplete burning of wood, as is illus- 
trated in the preparation of charcoal. 



* Rarely, or to a sUght extent, Uthiuni, rubirtiiim, iodine, bromine, 
lluorine, barium, coi^per, zinc, titanium, and boron. 



Fig. 1. 



IG now CROPS GROW. 

Exp. 2.— If a splinter of dry pine wood be set on fire and tlie burning 
end be gradually passed into the mouth of a narrow tube (see figure 1), 
whereby the supply of air is cvxt oft", or if it be thiaist into 
sand, the burning is incomplete, and a stick of charcoal re- 
mains. 

Cavhonizaiion and Charring are terms used to 
express the blackening of organic bodies by heat, 
and are due to the separation of carbon in the free 
or uncombined state. 

The presence of carbon in animal matters also is 
shown by subjecting them to incomj^lete com- 
bustion. 

Exp. 3.— Hold a knife-blade in the flame of a tallow candle ; 
the full access of air is thus i^revented, — a portion of carbon 
escapes combustion, and is deposited on tlie blade in the form 
of l(uni>-black. 

Oil of turpentine and petroleum (kerosene) contain so 
much carbon that a portion ordinarily escapes in the free 
state as smoke, when they are set on fire. 

When bones are strongly heated in closely-covered iron 
pots, until tliey cease yielding any vapors, there remains 
in the vessels a mixture of impure carbon with the earthy 
matter (phosphate of lime) of the bones, which is largely 
used in the arts, chiefly for refi^ning sugar, but also in the 
manufacture of fertilizers under the name of animal char- 
coal, or hone-hlach. 

Lignite, lituminous coal, anthracite, cohe — the porous, 
hard, and lustrous mass left when bituminous coal is 
heated with a limited access of air, and the metallic ap- 
pearing gas-carhon that is found lining the iron cylinders 
in which illuminating coal-gas is prepared, all consist 
largely or chiefly of carbon. They usually contain more 
or less incombustible matters, as well as a little oxygen, 
hydrogen, nitrogen, and sulphur. 

The different forms of carbon possess a greater or less 
degree of porosity and hardness, according to their origin 
and the temperature at which they are prepared. 

Carbon, in most of its forms, is extremely indestructi- 



THE VOLATILE PART OF PLANTS. 17 

ble under ordinary circumstances. Hence stakes and 
fence posts, if charred before setting in tlie ground, last 
much longer than when this treatment is neglected. 

The porous varieties of carbon, especially wood char- 
coal and bone-black, liave a remarkable power of absorb- 
ing gases and coloring matters, which is taken advantage 
of in the refining of sugar. They also destroy noisome 
odors, and are used for purposes of disinfection. 

Carbon is the characteristic ingredient of all organic 
compounds. There is no single substance that is the ex- 
clusive result of vital organization, no ingredient of the 
animal or vegetable produced by their growth, that does^ 
not contain this element. 

Oxygen. — Carbon is a solid, and is recognized by our 
senses of sight and feeling. Oxygen, on the other hand, 
is an air or gas, invisible, odorless, tasteless, and not dis- 
tinguishable in any way from ordinary air by the unas- 
sisted senses. 

It exists in the free (uncombined) state in the atmos- 
phere we breathe, but there is no means of obtaining it 
pure except from some of its compounds. Many metals 
unite readily with ox3^gen, forming compounds (oxides) 
which by heat separate again into their ingredients, and 
thus furnish the means of procuring pure oxygen. Iron 
and copper, wlien strongly heated and exposed to the air, 
acquire oxygen, but from the oxides of these metals 
(forge cinder, copper scale) it is not possible to separate 
pure oxygen. If, however, the metal mercury (quicksil- 
ver) be kept for a long time near the temperature at 
which it boils, it is slowly converted into a red powder 
(red precipitate, red oxide of mercury, or mercuric ox- 
ide), which on being more strongly heated is decomposed, 
yielding metallic mercury and gaseous oxygen in a pure 
state. 

The substance usually employed as the most convenient 
source of oxygen gas is the white salt called potassium 
2 



18 



now CROPS GROW. 



chlorate. Exposed to heat, this body melts, and present- 
ly evolves oxygen in great abundance. 

Exr. 4.-The foUowing figure iUustrates the apparatus employed for 
preparing and eollectiiig this gas. 

A tul)e of difficultly fusible glass, 8 inches long and i inch wide, con- 
tains tlic red oxide of mercury or potassium chlorate.* To its mouth is 
connected, air-tight, by a cork, a narrow tube, the free extremity of 
which passes under the shelf of a tub nearly filled with water. The 
shelf has, beneath, a funnel-shaped cavity opening above by a narrow 
orifice, over which a bottle filled with water is inverted. Heat being 




Fig. 2. 

applied to the wide tube, the common air it contains is first expelled, 
and presently, oxygen bubbles rapidly into the bottle and displaces 
the water. When the bottle is full, it may be corked and set aside, and 
its place supplied by another. Fill four pint bottles with the gas, and 
set them aside with their months in tumblers of water. From one 
ounce of potassium chlorate about a gallon of oxygen gas may be thus 
obtained, which is not quite pure at first, but becomes nearly so on 
standing over water for some hours. When the escape of gas becomes 
slow and cannot be quickened by increased heat, remove the delivery- 
tube from the water, to prevent the latter receding and breaking the 
apparatus. 

As this gas makes no peculiar impressions on the senses, 



* The potassium chlorate is best mixed with about one-qnarter its 
weight of powdered black oxide of manganese, as this facilitates the 
preparation, and renders the heat of a common alcohol lamp sufficient. 



THE VOLATILE PART OF PLANTS. 19 

wc employ its behavior toward other bodies for its recog- 
nition. 

Exp. 5. — Place a burning siiliuter of wood in a vessel of oxygen (lifted 
foi' that purpose, mouth upward, from the water). The lianie is at once 
greatly increased in brilliancy. Now remove the splinter froni the 
bottle, blow out the tlame, and thrust the still glowing point into the 
oxygen. It is instantly relighted. The experiment may be repeated 
many times. This is the usual test for oxygen gas. 

Combustion. — When the chemical union of two bodies 
takes place with such energy as to produce visible phe- 
nomena of fire or flame, the process is called combustion. 
Bodies that burn are combustibles, and the gas in which 
a substance burns is called a supporter of combustion. 

Oxygen is the grand supporter of combustion, and 
nearly all cases of burning met with in ordinary experi- 
ence are instances of chemical union between tlie oxygen 
of the atmosphere and some other body or bodies. 

The rapidity or intensity of combustion depends upon 
the quantities of oxygen and of the combustible that 
unite within a given time. Forcing a stream of air into 
a fire increases the supply of oxygen and excites a more 
vigorous combustion, whether it be done by a bellows or 
result from ordinary draught. 

Oxygen exists in our atmosphere to the extent of about 
one-fifth of the bulk of the latter. When a burning body 
is brought into unmixed oxygen, its combustion is, of 
course, more rapid than in ordinary air, four-fifths of 
which is a gas, presently to be noticed, that is compara- 
tively indifferent in its chemical afifinities toward most 
bodies. 

In the air a piece of hurniiig charcoal soon goes out ; 
but if plunged into oxygen, it burns with great rapidity 
and brilliancy. 

Exp. 6.— Attach a slender bit of charcoal to one end of a sharpened 
wire that is passed through a wide cork or card; heat the charcoal to 
redness in the flame of a lamp, and then insert it into a bottle of oxy- 
gen, Fig. 3. When the combustion has declined, a suitable test applied 



20 



HOW CROPS GROW. 



to tlie air of the bottle will demonstrate that another invisible gas has 
taken the place of the oxygen. 8ueh a test is lime-water* 
On pouring some of this into the bottle and agitating 
vigorously, the previously clear liquid becomes milky, 
and, on standing, a white deposit, or ijrecipitate, as the 
chemist terms it, gathers at the bottom of the vessel. 
Carbon, by tlms uniting to oxygen, yields carbonic acid 
gas, which in its turn combines with lime, producing 
carbonate of lime. These substances will be further 
noticed in a subsequent chapter. 

Metallic iron is incombustible in the at- 
mosphere nnder ordiniiry circumstances, but 
if heated to redness and brought into pure 
it burns as readily as wood burns in the air. 

EXP. 7.— Provide a thin knitting-needle, heat one end red hot, and 
sharpen it by means of a tile. Thrust the point thus 
made into a splinter of wood (a bit of the stick of a 
match, \ inch long); pass the other end of the needle 
through a wide, tlat cork for a support; set the wood on 
fire, and immerse the needle in a bottle of oxygen. Fig. 
4. After the wood consumes, the iron itself takes fire 
and burns with vivid scintillations. It is converted into 
two distinct ozides of iron, of which one,— ferric oxide,— 
will be found as a yellowish-red coating on the sides of 
the bottle; the other,— magnetic oxide,— will fuse to 
black, brittle globules, which falling, often melt quite 
into the glass. 





Fis:. 4. 



The only essential difference between these and ordi- 
nary cases of combustion is tlie intensity with which the 
process goes on, due to the more rapid access of oxygen 
to the comliustible. 

Many bodies unite slowly with oxygen, — oxidize, as it 
is termed, — without these phenomena of light and intense 
heat which accompany combustion. Thus iron rusts, lead 
tarnishes, wood decays. All these processes are cases of 
oxidation, and cannot go on in the absence of oxygen. 

Since the action of oxygen on wood and other organic 
matters at common temperatures appears to be analogous 

* To prepare lime-water, put a piece of unslaked lime, as large as a 
chestnut, into a pint of water, and after it has fallen to powder, agitate 
the whole f(U' a few minutes in a well-stoppered bottle. On standing, 
the oxeess of lime will settle, and the perfectly clear liquid above it is 
ready for use. 



THE VOLATILE PART OF PLAINTS. 21 

in a cliemical sense to actual burning, Liebig lias pro- 
posed the term eremaoausis (slow burning), to designate 
the chemical process of oxidation which takes place in 
decay, and which is concerned in many transformations, 
as in tlie making of vinegar and the formation of salt- 
peter.* 

Oxygen is necessary to organic life. The act of breath- 
ing introduces it into the lungs and blood of animals, 
where it aids the important office of respiration. Ani- 
mals, and plants as well, speedily j)erish if deprived of 
free oxygen, which has therefore been called vital air. 

Oxygen has a neai-ly universal tendency to combine/ 
with other substances, and form with them new com- 
pounds. With carbon, as we have seen, it forms carbonic 
acid gas or carbon dioxide. With iron it unites in vari- 
ous proportions, giving origin to several distinct oxides. 
In decay, putrefaction, fermentation, and respiration, 
numberless new products are formed, the results of its 
chemical affinities. 

Oxygen is estimated to be the most abundant body in 
nature. In the free state, but mixed with other gases, it 
constitutes one-fifth of the bulk of the atmosphere. In 
chemical union with other bodies, it forms eight-ninths 
of the weight of all the water of the globe, and one-third 
of its solid crust, — its soils and rocks, — as well as of all 
the plants and animals which exist upon it. In fact, 
there are but few compound substances occurring in or- 
dinary experience into which oxygen does not enter as a 
necessary ingredient. 

Nitrogen. — This body is the other chief constituent of 
the atmosphere, of which it makes up about four-fifths 
the bulk, and in which its office would appear to be 

* Recent investigation has demonstraterl that the oxidations which 
Liebic: classed under the term ereniacansis, are for the most part strict- 
ly dependent on the vital processes of extremely minute orj^anisms, 
which are in peneral characterized by the terms microbes or micro- 
demes, and are more specifically designated bacteria, i. e., "rod-shaped 
animalcules or plautlets." 



22 HOW CROPS GROW. 

mainly that of diluting and tempering the affinities of 
oxygen. Indirectly, however, it serves other most hn- 
porLant uses, as will presently be seen. 

For tlie preparation of nitrogen we have only to remove 
the oxygen from a portion of atmospheric air. Tiiis may 
be accomplished more or less i^erfectly by a variety of 
methods. We have just learned that the process of burn- 
ing is a chemical union of oxygen with the combustible. 
If, now, we can find a body which is very combustible 
and one which at the same time yields by union with ox- 
ygen a product that may be readily removed from the air 
in which it is formed, the preparation of nitrogen from 
ordinary air becomes easy. Such a body is jihosj^liorus, 
a substance to be noticed in some detail presently. 

Exr. 8.— The bottom of a dinner-plate is covered half an inch deep 
with water; a hit of chalk hollowed ont into a little cup is floated on 
the water by means of a large fiat cork or a piece of wood ; into this 
cup a morsel of dry pliosphorus as large as a pepper- .^J^ 

ct)rn is placed, which is then set on fire and covered by 
a capacious glass bottle or bell-jar. The jihosphorus 
burns at first with a vivid light, which is presently ob- 
scured by a cloud of snow-like phosphoric acid. The 
combustion goes on, however, until nearly all the oxy- 
gen is removed from the included air. The air is at 
first expanded by tlie heat of the flame, and a portion '^^^^^^^p 
of it escapes from the vessel; afterward it diminishes ^^^^^^^ 
in volume as its oxygen is removed, so that it is need- ■ j^j^^ g 

ful to pour Avater on the plate to prevent the external *'' 

air from passing into the vessel. After some time the white fume will 
entirely fall, and be absorbed by the water, leaving the inclosed nitro- 
gen quite clear. 

Exp. 0.— Another instructive method of preparing nitrogen is the fol- 
lowing: A handful of green vitriol (protosvdphate of iron or ferrous 
sulphate) is dissolved in half a pint of water, the solution is put into 
a qxiart bottle, a gill of ammonia-water or fresh potash-lye is added, 
tlie bottle stoppered, and the mixtiire vigorously agitated for some 
minutes; the stojiper is then lifted, to allow fresh air to enter, and the 
wliole is again agitated as before. This is repeated occasionally for half 
an hour or moie, until no further absorption takes place, when nearly 
l)ure nitrogen remains in tlie bottle. 

Free nitrogen, under ordinary circumstances, mani- 
fests no active properties, but is best characterized by its 
chemical indifference to most other bodies. That it is 



THE VOLATILE PAKT OF PLAKTS. 23 

inciipablc of supporting combustion is proved by the first 
method we have instanced for its preparation. 

Exp. 10. — A liurning splinter is immersed in the bottle containing the 
nitrogen prepared by the second method, Exp. 9; the llame immediate- 
ly goes out. 

Nitrogen cannot maintain respiration, so that animals 
perish if confined in it. Vegetation also dies in an at- 
mosphere of this gas. For this reason it was formerly 
called Azote (against life). In general it is difficult to 
effect direct union of nitrogen with other bodies, but at 
a high temperature, in presence of alkalies, it unites with 
carbon, forming cyanides. 

The atmosphere is the great store and source of nitro- 
gen in nature. In the mineral kingdom, especially in 
soils, it occurs in small relative proportion, but in large 
aggregate quantity as an ingredient of saltpeter and other 
nitrates, and of ammonia. It is a constant constituent 
of all plants, and in the animal it is a neyer-absent com- 
ponent of the working tissues, the muscles, tendons and 
nerves, and is hence an indispensable ingredient of food. 

Hydrogen. — Water, which is so abundant in nature, 
and so essential to organic existence, is a compound of 
two elements, viz. : oxygen, that has already been consid- 
ered, and hydrogen, which we now come to notice. 

Hydrogen, like oxygen, is a gas, destitute, when pure, 
of cither odor, taste, or color. It docs not occur nat- 
urally in the free state, except in small ([uantity in the 
emanations from boiling springs and volcanoes. Its most 
simple i)reparation consists in abstracting oxygen from 
water by means of agents which have no special afiinity 
for hydrogen, and therefore leave it uncoinbined. 

Sodium, a metal familiar to the chemist, has such an 
attraction for oxygen that it decomposes water with great 
rapidity. 

Exp. 11,— Hydrogen is therefore readily procured by inverting a bot- 
tle full of water in a bowl, and inserting into it a bit of sodium as large 
as a pea. The sodium shouhl first be wiped free from the naphtha iu 



24 



now CROPS GROW. 



which it is Iccpt, anrl then be wrapped tightly in several folds of paper. 
On brinj^ing it, thus prepared, under tlie mouth of the bottle, it floats 
upwartl, and when the water penetrates the paper, an abundant escape 
of gas occurs. 

Metallic iron, when at a red heat, rapidly decomposes 
water, uniting with oxygen and setting hydrogen free, 
as may be shown by passing steam from boiling water 
through a gun-barrel filled with iron-turnings and heated 
to bright redness. Certain acids which contain hydro- 
gen are decomposed by iron, zinc, and some other metals, 
their hydrogen being separated as gas, while the metal 
takes the place of the hydrogen with formation of a salt. 
Hydrochloric acid (formerly called muriatic acid) is a 
compound of hydrogen with chlorine, and may accord- 
ingly be termed hydrogen chloride. When this acid is 
poured upon zinc the latter takes the chlorine, forming 
zinc chloride, and hydrogen escapes as gas. Chemists 
represent such changes by the use of symbols (first letters 
of the names of chemical elements), as follows : 

gg} + Zn=Zn^; + gor 
2 (H CI) + Zn = Zn Clj + Ha 

Exp. 12.— nito a bottle fitted with cork, funnel, and delivery tubes (Fig. 
6) an ounce of iron tacks or zinc 
clippings is introduced, a gill 
of water is poured upon tlicni, 
and lastly an ounce of hydro- 
chloric acid is added. A brisk 
effervescence shortly com- 
mences, owing to the escaiae 
of nearly pure hydrogen gas, 
wliicli may be collected in a 
bottle filled with water as di- 
rected for oxygen. The first 
portions that pass over are 
mixed with air, and sliotdd be 
rejected, as the mixture is dan- 
gerously explosive. 



One of the most strik- 
ing properties of free hy- 




Fig. 6. 



drogen is its levity. It is the lightest body in nature 



THE VOLATILE PART OF PLAi^TS. 



25 



that has been weighed, being fonrteen and a half times 
lighter than common air. It is hence 
^nsedjn filling balloons. Another jn-operty 
is its combustibility ; it inflames on contact 
with a lighted taper, and burns with a 
flame that is intensely hot, though scarcely 
luminous if the gas be pure. Finally, it 
is itself incapable of supporting the com- 
bustion of a taper. 




Fig. 7. 



Exp. 13.— An tliese characters may be shown by the foUowing single 
experiment. A bottle full of hydrogen is lifted from tlie Avater over 
which it has been collected, and a taper attached to a bent wire, Fig. 7, 
is brought to its mouth. At first a slight explosion is heard from the 
sudden burning of a }nixture of the gas with air that forms at tlie mouth 
of the vessel ; then the gas is seen burning on its lower surface Avith a 
pale flame. If now the taper be passed into the bottle it will be extin- 
guished; on lowering it again, it will be relighted by the burning gas; 
finally, if the bottle be suddenly turned mouth upwards, the light hy- 
drogen rises in a sheet of flame. 

In the above experiment, the hydrogen burns only 
where it is in contact with atmospheric oxygen ; the pro- 
duct of the combustion is an oxide of hydrogen, the uni- 
versally diffused compound, water. The conditions of 
the last experiment do not permit the collection or iden- 
tification of this water ; its production can, however, 
readily be demonstrated. 

Exr. II.— The arrangement shown in Fig. 8 may be employed to exhibit 




Fig. 8. 

the formation of water by the burning of hydrogen. Hydrogen gas is 
generated from zinc and dilute acid in the two-necked bottle. Thus 



2G now CROPS GKOW. 

produced, it is niingletl with spray, to remove which it is made to 
stream througli a tube loosely filletl with cotton. After air has been 
entireiij dispLaced from the apparatus, the gas is ignited at the up- 
curved end of the narrow tube, and a clean bell-glass is supported over 
the flame. Water collects at once, as dew, on the interior of the bell, 
and shortly flows down in drops into a vessel placed beneath. 

Ill the mineral world we scarcely find hydrogen occur- 
ring in nmcb quantity, save as water. It is a constant 
ingredient of plants and animals, and of nearly all the 
numberless substances which are products of organic life. 

Hydrogen forms with carbon a large number of com- 
pounds, the most common of which are tlie volatile oils, 
like oil of turpentine, oil of lemon, etc. The chief illu- 
minating ingredient of coal gas (ethylene or olefiant gas), 
the coal or rock oils (kerosene), together with benzine 
and paraffin e, are so-called hydro-carbons. 

Sulphur is a well-known solid substance, occurring in 
commerce either in sticks (brimstone, roll sulphur) or as 
a fine powder (flowers of sulphur), having a pale yellow 
color, and a peculiar odor and taste. 

Uncombined sulphur is comparatively rare, the com- 
mercial supplies being almost exclusively of volcanic ori- 
gin ; but, in one or other form of combination, this ele- 
ment is universally dilfused. 

Sulphur is combustible. It burns in the air with a 
pale blue ihimo, in oxygen gas with a beautiful purple- 
blue llame, yielding in both cases a suffocating and fum- 
iu'^ gas of peculiai* nauseous taste, which is called sul- 
2)hurou^ acid gas or sidplmr dioxide. 

Exp. 15.— Heat a bit of sulphur as large as a grain of wheat on a slip 
of iron or glass, over the flame of a spirit lamp, for observing its fusicni, 
combustion, and the development of sulphur dioxide. Further, scoop 
out a little hollow in a piece of chalk, tAvist a wire round the latter to 
serve for a handle, as in Fig. 3; heat the chalk with a fragment of sul- 
phur upon it until the latter ignites, and bring it into a bottle of oxygen 
gas. The purple flame is shortly obscured by an oi)aque white fume of 
sulphur dioxide. 

Sulphur forms with oxygen another compound, the tri- 
oxide, which, in combination with water, constitutes coni- 



THE VOLATILE PART OF PLANTS. 27 

mon suljmiiric acid, or oil of vitriol. This oxide is devel- 
oped to a slight extent during the combustion of sulphur 
in the air and the acid is prepared on a large scale for 
commerce by a complicated process. 

Sulphur unites with most of the metals, yielding com- 
pounds known as suljjliides, or formerly as stdphurets. 
These exist in nature in large quantities, especially the 
sulphides of iron, copper, and lead, and many of them 
are valuable ores. Sulphides may be formed artificially 
by heating most of the metals with sulphur. 

Exp. 1G. — Heat the bowl of a tobacco-i^ipe to a low red heat in a stove 
or furnace ; have in readiness a thin iron wire or watch-spring made 
into a sjjiral coil ; throw into the i^ipe-bowl some lumps of sulphur, and 
when tiiese melt and boil, with formation of a red vapor or gas, intro- 
duce the iron coil, pi'eviously heated to redness, into the sulphur vai^or. 
The sulphur and iron unite; the iron, in fact, burns in the sulphur gas, 
giving rise to a black iron sulphide, in the same manner as in Exp. 7 it 
burned in oxygen gas and produced an iron oxide. The iron sulphide 
melts to brittle, round globules, and remains in the pipe-bowl. 

With hydrogen, the element we are now considering 
unites to form a gas that possesses in a high degree the 
odor of rotten eggs, and is, in fact, the chief cause of the 
uoisomeness of tliis kind of putridity. This gas, com- 
monly called sulphuretted hydrogen, or hydrogen sulphide, 
is dissolved in, and evolved abundantly from, the water 
of sulphur springs. It may bo prodncod artificially by 
acting on some metallic sulphides with dilute sulphuric 
or hydrochloric acid. 

Exp. 17. — Place a lump of the iron sulphide i")repared in Exj?. 16 in a cup 
or wine-glass, add a little water, and lastly a little hydrochloric acid, 
iiubbles of hydrogen sulphide will shortly escape. 

In soils, sulphur occurs almost invariably in the form 
of sulphates, compounds of sulphuric acid with metals, a 
class of bodies to be hereafter noticed. 

In plants, sulphur is always present, though usually in 
small proportion. The turnip, the onion, mustard, horse- 
radish, and assafoBtida owe their peculiar flavors to vola- 
tile oils of which sulphur is an ingredient. 



28 now CHOPS grow. 

Albumin, globulin, casein and similar principles, never 
absent from plant or animal, possess also a small con- 
tent of sulphur. In hair and horn it occurs to the amount 
of three to five per cent. 

When organic matters are burned with full access of 
air, their sulphur is oxidized and remains in the ash as 
sulphates, or escapes into the air as sulphur dioxide. 

Phosphorus is an element which has such intense af- 
finities for oxygen that it never occurs naturally in the 
free state, and when prepared by art, is usually obliged to 
be kept immersed in water to prevent its oxidizing, or 
even taking fire. It is known to the chemist in the solid 
state in two distinct forms. In the more commonly oc- 
curring form, it is colorless or yellow, translucent, wax- 
like in appearance ; is intensely poisonous, inflames by 
moderate friction, and is luminous in the dark ; hence its 
name, derived from two Greek words signifying light- 
hearer. The other form is brick-red, ojoaque, far less in- 
flammable, and destitute of poisonous properties. Phos- 
phorus is extensively employed for the manufacture of 
friction matches. For this purpose yellow phosphorus is 
chiefly used. When burned in air or in oxygen gas this ele- 
ment forms a white substance — phosphorus pentoxide 
(formerly termed anhydrous phosphoric acid) — which dis- 
solves in water, at the same tim^ uniting chemically with 
a portion of the latter, and thus yielding a body of the 
utmost agricultural importance, viz., phosplioric acid. 

Exp. 18.— Burn a bit of phosphorus under a bottle, as in Exp. 8, omit- 
ting the water on tlie plate. The snow-like cloud of phosphorus pen- 
toxide gathers partly on the sides of the bottle, but mostly on the plate. 
It attracts moisture Avhen exjwsed to the air, and hisses from develoi> 
nient of heat when put into water. Dissolve a portion of it in hot 
water, and observe that the solution is acid to the taste. Finally evapo- 
rate the solution to dryness at a gentle heat. Instead of recovering 
thus the wliite opaque phosphoriis pentoxide, the residue is a trans- 
parent mass of phosphoric acid, a compound of phosphorus, oxygen 
and hydrogen. 

In nature phosphorus is usually found in the form of 



THE VOLATILE PART OF PLAN"TS. 29 

pliospliates, which are phosphoric acid whose hydrogen 
has been partly or entirely replaced by metals. 

In plants and animals, it exists for the most part as 
phosphates of calcium (or lime), magnesium (or mag- 
nesia), potassium (or potash), and sodium (or soda). 

The bones of animals contain a considerable proportion 
(10 per cent.) of phosphorus, mainly in the form of cal- 
cium phosphate. It is from this that the phosphorus 
employed for matches is largely procured. 

Exr. 19. — Burn a piece of bone in a fire until it becomes white, or 
nearly so. The bone loses about half its weight. AVhat remains is 
bone-earth or bone-ash, and of this 90 per cent, is calcium phosphate. 

Phosphates are readily formed by bringing together 
solutions of various metals with solution of phosphoric 
acid. 

Exp. 20.— Pour into each of two wine or test glasses a small quantity 
of the solution of pliosi)lioric acid obtained in Exjj. 18. To one, add 
some lime-water (see note p. 19) until a white cloud or 2)rGcipitate is per- 
ceived. This is a calcium phosphate. Into the other portion droxi solu- 
tion of alum. A translucent cloud of aluminiam pliosphate is immedi- 
ately produced. 

In soils and rocks, phosphorus exists in the state of 
pliospliates of calcium, ahiminium, and iron. 

Tlie tissues and juices of animals and plants generally 
contain small proportions of several highly complex " or- 
ganic compounds" in which phosphoric acid is associated 
with the elements carbon, oxygen, hydrogen and nitrogen. 
Such substances are chlorophyll, lecithin and nuclein, 
to be noticed hereafter. 

We have thus briefly considered the more important 
characters of those six bodies which constitute that part 
of plants, and of animals also, which is volatile or de- 
structible at high temperatures, viz. : carbon, hydrogen, 
oxygen, nitrogen, sulphur, and phosphorus. 

Out of these substances, which are often termed the 
organic elements of vegetation, are chiefly compounded all 
the numberless products of life to be met with, either in 
the. vegetable or animal world. 



d') now CROPS GROW. 

ULTIMATE COMPOSITION" OF VEGETABLE MATTER. 

To convey an idea of the relative proportions in which 
these six elements exist in plants, a statement of the 
ultimate or elementary percentage composition of several 
kinds of vegetable matter is here subjoined. 

Grain of Sfraip of Tubers of Grain of Hay of Red 
Wneut. Wlieut. totalo. Peas. Clover. 

Carbon 46.1 48.4 44.0 46.5 47.4 

Hvdroo-en 5.8 5.3 5.8 _ 6.2 5.0 

olv<4i 43.4 38.9 4-1.7 40.0 37.8 

MtTogei;.;:::: ^-^ 0.4 1.5 4.2 2.1 

Ash, incliuling sulphur J 04 7.0 4.0 3.1 7.7 

and phosphorus ) 

100.0 100.0 100.0 100.0 100.0 

S,,],.]..,,. 0.12 0.14 0.08 0.21 0.18 

Phosphorus.:: 0.30 0.80 0.34 0.34 0.20 

Our attention may now be directed to the study of such 
compounds of these elements as constitute the basis of 
plants in general ; since a knowledge of them will pre- 
pare us to consider the remaining elements with a greater 
degree of interest. 

Previous to this, however, we must, first of all, gain a 
clear idea of that force— chemical affinity — in virtue of 
whose action these elements are held in their combina- 
tions and, in order to understand the language of chem- 
ical science, must know something of the views that now 
prevail as to the constitution of matter. 

§ 3. 

CHEMICAL AFEIinTY. — THE ATOMIC-MOLECULAR THEORY. 

Chemical Attraction or Affinity is that force or 
Myid of energy which unites or combines tiuo or more sub- 
stances of unWce character^ to a new body different from 
its ingredients. 

Chemical Combination differs essentially from mere 
mixture. Tiius v/e may put together in a vessel the two 
gases, ox3^gen and liydrogcn, and they will remain uncom- 
bined for an indciiniie time, occupying their original vol- 



THE VOLATILE PART OF PLANTS. -31 

lime ; but if a flame be brought into the mixture they in- 
stantly unite with a loud explosion, and, in place of the 
light and bulky gases, we find a few drops of water, which 
is a liquid at ordinary temperatures, and in winter 
weather becomes solid, which does not sustain combus- 
tion like oxygen, nor itself burn as does hydrogen; but 
is a substance haying its own peculiar properties, differ- 
ing from those of all other bodies with which we are ac- 
quainted. 

In the atmosphere we have oxygen and nitrogen in a 
state of mere mixture, each of these gases exhibiting its 
own characteristic properties. When brought into chem- 
ical combination, they are capable of yielding a series of 
no less tlian live distinct compounds, one of which is the 
so-called laughing-gas, while tlie others form suffocating 
and corrosiye vapors that are totally irresjnrable. 

Chemical Decomposition. — Water, thus composed 
or put together by the exercise of affinity, is easily de- 
composed or taken to pieces, so to speak, by forces that 
oppose affinity — e. g., heat and electricity — or by the 
greater affinity of some other body — e. g., sodium — as al- 
ready illustrated in the preparation of hydrogen, Exp. 11. 

Definite Proportions. — A further distinction be- 
tw^een chemical union and mere mixture is, that, while 
two or more bodies may, in general, be mixed in all pro- 
portions, bodies combine chemically in comparatively 
few proportions which are fixed and invariable. Oxygen 
and hydrogen, e. g., are found united in nature, princi- 
pally in the form of water ; and water, if pure, is always 
composed of one-ninth hydrogen and eight-ninths oxy- 
gen by Vi^eight, or, since oxygen is, bulk for bulk, sixteen 
times heavier than hydrogen, of one volume or measure 
of oxygen to two volumes of hydrogen. 

Atoms. — It is now believed that matter of all kinds 
consists of 'indivisible and unchangeable particles called 
atoms, which are united to each other by chemical at- 



32 HOW CHOPS grow. 

tniction, and cannot ordinarily exist in the free state. 
On this view each particular kind of matter or chemical 
substance owes its individuality either to the special kinds 
or to the numbers of the atoms it consists of. Atoms 
may be defined as the smallest quantities of matter which 
can exist in chemical combination and the smallest of 
which we have any knowledge or conception. 

Atomic Weight of Elements. — On the hypothesis 
that chemical union takes place between atoms of the 
elements, the simplest numbers expressing the propor- 
tions by weight* in which the elements combine, are ap- 
propriately termed atomic lueights. These numbers are 
only relative, and since hydrogen is the element which 
unites in the smallest proportion by weight, it is assumed 
as the standard unit. From the results of a great 
number of the most exact experiments, chemists have 
generally agreed upon the atomic weights given in the 
subjoined table for the elements already mentioned or 
described. 

Symbols. — For convenience in representing chemical 
changes, the first letter (or letters) of the Latin name 
of the element is employed instead of the name itself, and 
is termed its symbol. 

TABLE OF ATOMIC WEIGHTS AND SYMBOLS OF ELEMENTS-t 

Element. Atomic We'Kjht. Symbol. 





Hydrogen 


1 


H 




Carbon 


12 


C 




Oxygen 


IG 


o 




Nitrogen 


14 


N 




Sulphur 


32 


S 




Phosphorus 


31 


P 




Chlorine 


35.5 


c\ 




Mercury 


200 


Hg (Hyrtrargyrum) 




Potassium 


39 


K (Kaliuni) 




Potlium 


23 


Na (Natrium) 




Calcium 


40 


C'a 




Iron 


56 


Fe (Ferrum) 



* Unless otherwise stated, parts or proportions by weight are always 
to be understood. 

t Now, chemists receive as the true atomic weights donhle th-3 num- 
bers that were formerly employed, those of hydrogen, chlorine and a 
few others excepted. The atomic weights here given are mostly whole 
numbers. The actual atomic weiglits, as experimentally determined, 
differ from the above by small fractions, which may be neglected. 



THE VOLATILE PART OF PLANTS. 33 

Multiple Proportions. — When two or more bodies 
unite in. several proportions, their quantities, when not 
expressed by the atomic weights, are twice, thrice, four, 
or more times, these weights ; they are multiples of the 
atomic weights by some simple number. Thus, carbon 
and oxygen form two commonly occurring compounds, 
viz., carhoii monoxide, consisting of one atom of each in- 
gredient, and carlon dioxide, which contains to one atom, 
or 12 parts by weight, of carbon, two atoms, or 32 parts 
by weight, of oxygen. 

Molecules* contain and consist of chemically-united 
atoms, and are the smallest particles of matter that can 
have an individual or physical existence. AVhile the 
atoms compose and give character to the molecules, the 
molecules alone are sensibly known to us, and they give 
cliaracter to matter as we find it in masses, either solid, 
liquid or gaseous. In solids the molecules more or less 
firmly cohere together ; in liquids they have but little 
cohesion, and in gases they are far apart and tend to sepa- 
rate from each other. Tlie so-called ^^ elements" are, in 
fact, mostly compounds whose molecules consist of two 
or more like atoms, while all other chemical substances 
are compounds whose molecules are made up of two or 
more unlike atoms. 

Molecular Weights of Compounds. — The mole- 
cular weight of a compound is the sum of the weights of 
the atoms that compose it. For example, water being 
composed of 1 atom, or 16 parts by weight, of oxygen, 
and 2 atoms, or 2 parts by weight, of hydrogen, has the 
molecular weight of 18. f 

The following scheme illustrates the molecular compo- 
sition of a somewhat complex compound, one of the car- 



* Latin diminutive, signifying a little mass. 

t We must refer to reeejit treatises on chemistry for fuller informa- 
tion as to atoms and molecules and tlie methods of finding the atomic 
and molecular weights. 



34 HOW CROPS GROW. 

bonatos of ammoniiiTn, which consists of four elements, 
ten atoms, and has a molecular weight of S3venty-nine. 

Ammonia gas results from the union of an atom of 
nitrogen with three atoms of liydrogen. One molecule 
of ammonia gas unites with a molecule of carbon dioxide 
gas and a molecule of water to produce a molecule of 
ammonium carbonate. 

Atoms. Atomic Molecular 
weights, weights. 



Ammonium 
Carbonate 
1 mol. 



Ammonia (Hydrogen, 3 = 3 ) _,,. 

Imol. — I Nitrogen, 1 = 14 | — ^' 

Carbon di- (Carbon, 1 ^ 12 ( ^^ 

oxide 1 mol. (Oxygen, 2 =: 32 I ~ 

Water, _( Hydrogen, 2 =. 2 i _.^> 

1 = 10 j — ^^ 



79 



1 mol. I Oxygen, 

Notation and Formulas of Compounds. — For the 

purpose of expressing easily and concisely the composi- 
tion of compounds, and the chemical changes they 
undergo, chemists have agreed to make the symbol of an 
element signify one atom of that element. 

Thus H implies not only the light, combustible gas 
hydrogen, but also one part of it hy weigld as compared 
with other elements, and S suggests, in addition to the 
idea of the body sulphur, the idea of 32 parts of it by 
weight. Through this association of the atomic weight 
with the symbol, the composition of compounds is 
expressed in the simplest manner by writing the symbols 
of their elements one after the other. Thus, carbon 
monoxide is represented by CO, mercuric oxide by HgO, 
and iron monosulphidc by FeS. The symbol 00 con- 
veys to the chemist not only the fact of the existence 
of carbon monoxide, but also instructs him that its mole- 
cule contains an atom each of carbon and of oxygen, and 
from his knowledge of the atomic weights he gathers the 
proportions by weight of the carbon and oxygen in it. 

When a compound contains more than one atom of an 
element, this is shown by appending a small figure to the 
symbol of the latter. For example : water consists of 
two atoms of hydrogen united to one of oxygen, and ita 



THE VOLATILE PART OF PLAINTS. 35 

symbol is HgO. In like manner the symbol of carbon 
dioxide is CO2. 

When it is wished to indicate that more than one mole- 
cnle of a compound exists in combination or is concerned 
in a chemical change, this is done by prefixing a large 
figure to the symbol of the compound. For instance, 
two molecules of water are expressed by 2 H2O. 

The symbol of a compound is usually termed a formula 
and if correct is a molecular formula and shows the com- 
position of one molecule of the substance. Subjoined is 
a table of the molecular formulas of some of the com- 
pounds that have been ah-eady described or employed. 

FORMULAS OF COMPOUNDS. 

Water 

Hydrogen Sulphide 
Iron Monosuli)hide 
Mercuric Oxide 
Carbon Dioxide 
Calcium Chloride 
Sulphur Dioxide 
Sulph^ir Trioxirle 
Phospliorus Pentoxide 

Empirical and Rational Formulas. — It is obvious 
that many different formulas can be made for a body of 
complex character. Thus, the carbonate of ammonium, 
whose composition has already been stated (p. 33), and 
which contains 

1 atom of Nitrogen, 
1 atom of Carbon, 
3 atoms of Oxygen, and 
5 atoms of Hydrogen, 

may be most compactly expressed by the symbol 

NCOsH.T 

Such a formula merely informs us what elements and 
liow many atoms of each element enter into the compo- 
sition of the substance. It is an empirical formula, 
being the simplest expi-ession of the facts obtained by 
analysis of the substance. 

Rational formulas, on the other hand, are intended to 
convey some notion as to the constitution, formation, or 



Formula. 


Aloleeular Weight, 


H2O 


18 


PI,S 


34 


FeS 


88 


HgO 


216 


CO, 
CaCk 


44 


111 


SO2 


64 


SO, 


80 


p,o, 


142 



3G HOW CROPS GROW. 

modes of decomposition of the body. For example, the 

real arran2:ement of the atoms in ammonium carbonate 

is believed to be expressed by the rational (or structural) 

formula 

o~c/^-^ H, 

'^— '-\0— H 

in which the carbon is directly united to oxygen, to 
which latter one hydrogen and the nitrogen are also 
linked, the remaining hydrogens being combined to the 
nitrogen. 

Valence. — The connecting lines or dashes in the fore- 
going formula show the valence of the several atoms, i. e., 
their "atom-fixing power." The single dash from H 
indicates that hydrogen is univalent or has a valence of 
one. The two dashes connected with express the 
hivalence of oxygen or that the atom of this element can 
combine with two hydrogens or other univalent atoms. 
The nitrogen is united on one hand with 4 hydrogen 
atoms, and also, on the other hand, satisfies half the val- 
ence of oxygen ; it is accordingly quinquivalent, i. e., has 
five units of valence. Carbon is quadrivalent, being 
joined to oxygen by four units of valence. 

Equations of Formulas serve to explain the results 
of chemical reactions and changes. Thus, the breaking 
up by heat of potassium chlorate into potassium chloride* 
and oxygen is expressed by the following statement: 

Potassium Chlorate. Potassium ndoride. Oxyqen. 

2KCIO3 r= 2KC1 + 3 O2 

The sign of equality, =, shows that what is written 
before it supplies and is resolved into what follows it. 
The sign -|- indicates and distinguishes separate com- 
pounds. 

The employment of this kind of short-hand for exhib- 
iting chemical changes will find frequent illustration as 
we proceed with our subject. 

Modes of Stating Composition of Chemical 



THE VOLATILE PART OF PLAINTS. 37 

Compounds. — These are two: 1, atomic or molecular 
statements, and 2, cetitesimal scatements, or proportions 
in one hundred parts (per cent, p. c., or %). Those 
modes of expressing composition arc very useful for com- 
paring together different compounds of the same ele- 
ments, and, while usually the atomic statement answers 
for substances which are comparatively simple in their 
composition, the statement per cent is more useful for 
complex bodies. The compocition of the two compounds 
of carbon with oxygen is given below according to both 
methods. 

Atomic. Per cent. Atomic. Percent. 

Carbon (C), 12 42.86 (C) 12 27.27 

Oxygen (O), IG 57.14 (O2) 32 72.73 



Carbon Monoxide (CO), 28 100.00 Carbon Dioxide (COg), 44 100.00 

The conversion of one mode of statement into the other is a ease of 
simple rule of tliree, whicli is illustrated in tlie following calculation 
of the centesimal composition of water from its molecular formula. 

Water, H2O, has the molecular weight 18, i. e., it consists of two 
atoms of hydrogen, or two parts, and one atom of oxygen, or sixteen 
X)arts by weight. 

The arithmetical i^roportions subjoined serve for the calculation, viz. : 

H,0 Water H Hydrogen 

18 : 100 : : 2 : per cent sought (=11.11) 

H,0 Water O Oxygen 

18 : 100 : : 16 : per cent sought (=88.89) 

By miiltiplying together the second and third terms of these propor- 
tions, and dividing by the first, we obtain the recpiiredper cent, viz., of 
hydrogen, 11.11 ; and of oxygen, 88.89. 

The reader must bear well in mind that chemical affin- 
ity manifests itself with very different degrees of inten- 
sity between different bodies, and is variously modified, 
excited, or annulled, by other natural agencies and forces, 
especially by heat, light and electricity. 

§4. 

VEGETABLE ORGANIC COMPOUNDS, OR PROXIMATE 
PRINCIPLES. 

We are now prepared to enter upon the study of the 
organic compounds, which constitute the vegetable struc- 



h 



38 now CROPS grow. 

ture, and which are prodnced from the elements carbon, 
oxygen, hydrogen, nitrogen, sulphur, and phosphorus, by 
chemical agency. The number of distinct substances 
found in plants is practically unlimited. There are 
already well known to chemists hundreds of oils, acids, 
bitter principles, resins, coloring matters, etc. Almost 
every plant contains some organic body peculiar to itself, 
and usually the same plant in its difLcrent parts reveals 
to the senses of taste and smell the presence of several 
individual substances. In tea and coffee occurs an 
intensely bitter ''active principle," caffeine. From 
tobacco an oily liquid of eminently narcotic and poison- 
ous properties, nicotine, can be extracted. In the orange 
are found no less than three oils ; one in the leaves, one 
in the flowers, and a third in the rind of the fruit. 

Notwithstanding the great number of bodies thus 
occurring in the vegetable kingdom, it is a few which 
form the bulk of all plants, and especially of those which 
have an agricultural importance as sources of food to 
man and animals. These substances, into which any 
plant maybe resolved by simple, partly mechanical means, 
are conveniently termed proximate princirjles, and we 
shall notice them in some detail under eight princij)al 
classes, viz. : 

1. Water. 

•V^ 2. The CARBnYDRATES. 

, 7 '■ 3. The Vegetable. Acids. 

, ^ } 4. The Fats and Oils. 

c, 7 5. The Albuminoids or Proteik Bodies and Fer- 



ments. 



^ I / V 6. The Amides. 

yi'^o 7. The Alkaloids. 

^ I i, V 8. Phospiiorized Substances. 

I. Water, HgO, as already stated, is the most abund- 
ant ingredient of plants. It is itself a compound of 
oxygen and hydrogen, having the following centesimal 
composition : 



TKE VOLATILE PART OF PLAINTS. 



39 



Oxygen , 88.89 

Hydrogen 11.11 

100.00 

It exists in all parts of plants, is the immediate cause 
of the succulence of their tender portions, and is essen- 
tial to the life of the vegetable organs. 

ni tlie foUowing table are given the percentages of water in some of 
tlie more common agricultural products in the fresh state, but the pro- 
j)ortions are not quite constant, even in the same part of different 
specimens of any given plant. 

AVATER IN FllESH PLANTS. (PEK CENT.) 

Average. Ilanf/c. 

Meadow grass 71 60 to 78 

Red clover 80 68 " I'G 

Maize, as used for ft)dder 82 71 " '.>;J 

Cabbage 85 80 " M 

Potato tubers 75 77 " »2 

Sugar beets 81 76 " 'jO 

Carrots 86 70 "00 

Turnips 01 86 "03 

In living plants^ water is usually perceptible to the 
eye or feel, as saj:). But ifc is not only fresh plants that 
contain water. When grass is made into hay, the water 
is by no means all dried out, but a considerable propor- 
tion remains in the pores, which is not recognizable by 
the senses. So, too, seasoned wood, flour, and starch, 
when seemingly dry, contain a quantity of invisible 
water, which can])e removed by heat. 

Exp. 21.— Into a wide glass tube, like that shoAvn in Fig. 2, place a 
spoonful of saAV dust, or starch, or a little hay. Warm over a lamp, 
but very sh>wly and cautiously, so as not to burn or blacken tlie sub- 
stance. Water will be expeUed from the organic matter, and will col- 
lect on the cold i>art of tlie tube. 

It is thus obvious that vegetable substances may con- 
tain water in at least tivo different conditions. Eod 
clover, for example, when growing or 
freshly cut, contains about 80 per cent of 
water. When the clover is dried, as for 
making hay, the greater share of this wa- 
ter escai)es, so that the air-dry plant con- 
tains but about 15 per cent. On subject- 
ing the air-dry clover to a temperature 
of 312 ° for some hours, the water is completely expelled, 
and the substance becomes really dry, i. c., icater-free. 




Fii 



40 HOW CROPS GROW. 

To drive off all water from vegetable matters, the chemist usually 
employs a 'water-oven, Fig. 9, consisting of a vessel of tin or copper 
plale, with double walls, between which is a space that may be half 
filled with Avater. Tlie substance to be dried is pla,ced in the interior 
chamber, the door is closed, and the water is brought to boil by the 
heat of a lamp or stove. The precise quantity of \^ater belonging to, 
or contained in, a substance, is ascertained by first weighing the sub- 
stance, then drying it until its weight is constant. The loss is water. 

In the subjoined table are given tlie average quantities, per cent, of 
water existing in various vegetable products when air-dry. 

WATER IN AIR-DRY PLANTS. PER CENT. 

Meadow grass (hay) 15 

Red clover hay 17 

Pine wood 20 

Straw and chaff of wheat, rye, etc 15 

Bean straw 18 

Wheat (rye, oat) kernel 14 

Maize kernel 12 

That portion of the water wliicli the fresh plant loses 
by mere exposure to the air is chiefly the water of its 
juices or sap, and, on crushing the fresh i3lant, is mani- 
fest to the sight and feel as a liquid. It is, properly speak- 
ing, the free ivatcr of vegetation. The water which 
remains in the air-dry plant is imperceptible to the senses 
while in the plant, — can only be discovered on expelling 
it by heat or otherwise, — and may be designated as the 
hygroscopic or combined water of vegetation. 

The amount of water contained in either fresh or air- 
dry vegetable matter is somewhat fluctuating, according 
to the temperature and the dryness of the atmosi)here. 

2. The Carbhydrates. This group falls into three 
subdivisions, viz. : 

a. The Amyloses, comprising Cellulose, Starch, Inu- 
lin, Glycogen, the Dextrins and Gums, having the 
formula (CoHio05)n. 

h. The Glucoses, which include Dextrose, Levulose, 
Galactose and similar sugars, having the composition 
OeHisOe. 

c. The Sucroses, viz. : Cane Sugar or Saccharose, 
Maltose, Lactose and other sugars, whose formula in 
most cases is Ci2Hij20ii. 



THE VOLATILE PART OF PLANTS. 



41 



On account of their abundance and uses the Carbhy- 
drates nink as the mostim2:»oi'tcint class of vegetable sub- 
stances. Their name refers to the fact that they consist 
of Carbon, Hydrogen and Ox^^gen, the last two elements 
being always present in the same proportions tliat are 
found in waiter. 

These bodies, especially cellulose and starch, form by 
far the larger share — perhaps seven-eighths — of all the dry 
matter of vegetation, and most of them are distributed 
throughout all parts of plants. 

a. The Amylases. 

Cellulose (CcHio05)n. — Every agricultural plant is 
an aggregate of microscopic cells, i. e., is made up of 
minute sacks or closed tubes, adhering to each other. 

Fig. 10 represents an extremely thin slice from the stem of a cahltage, 
magnified 230 diameters. The united walls of two eells are seen in sec- 
tion at a, while at b an empty space is noticed. 




Fig. 10. 



The outer coating, or wall, of the vegetable cell con- 
sists chiefly or entirely of cellulose. This substance is 
accordingly the skeleton or framework of the plant, and 
the material that gives toughness and solidity to its parts. 
Next to water it is the most abundant body in the vege- 
table world. 



42 



HOW CROPS GROW. 



Nearly all plants and all their parts contain cellulose, 
but it is relatively most abundant in 
stems and leaves. In seeds it forms a 
large portion of the husk, shell, or other 
outer coating, but in the interior of the 
seed it exists in small proportion. 

The fibers of cotton (Fig. 11, a), hemp, 
and flax (Fig. 11, ^), and white cloth and 
unsized paper made from these materials, 
arc nearly pure cellulose. 

The fibers of cotton, hemi?, and tlax are simi)ly 
lung and thick-waned ceUs, the appearance of 
which, when highly magnified, is shown in Fig. 11, 
where a represents the tliinner, more soft, and col- 
lapsed cotton fiber, and b the thicker and more dur- 
able fiber of linen. 

Wood, or woody fiber, consists of long 
and slender cells of various forms and di- 
mensions (see p. 293), which are delicate 
when young (in the sap wood), but as 
they become older fill up interiorly by the deposition of re- 
peated layers of cellulose, which is more or less inter- 
grown with other substances.* The hard shells of nnts 
and stone fruits contain a basis of cellulose, which is im- 
pregnated with other matters. 

When quite pure, cellulose is a white, often silky or 
spongy, and translucent body, its appearance varying 

* Wood was formerly supposed to consist of cellulose and so-called 
"lignin." On this view, according to F. Schulze, liunin impregnates 
(not simply incrusts) tlie cell-wall, is sobilile in hot alkaline solutions, 
and IS readily oxicHzed by nitric acid. Schulze ascribes to it the com- 
position 

Carbon 55.3 

Hydrogen r>.9, 

Oxygen 38.9 




100.0 



This is, however, simply the inferred composition of what is left after 
the cellulose, etc., have beeu removed. " Li^niin " cannot be separated 
in t!ic pure stale, and l>;is never been analyzed. What is thus desig- 
nal e<l is ;i mixture of several distinct substances. Fremy's liirnose, lig- 
none, liguiu, and Ihaiireose, as well as J. Erdinan's tilycolignose and 
lignose, are not established as chemically distinct substances. 



TUE VOLATILE L'AllT Oh' PLANTS. io 

somewhat according to the soarce whciico it is obtained. 
In the air-dry state, at common temperatures, it usually 
contains about 10 % of hygroscopic wiiter. It has, in 
common with animal membranes, the character of swell- 
ing up when immersed in water, from imbibing this 
liquid ; on drying again, it shrinks in bulk. It is tough 
and elastic. 

Cellulose, as it naturally occurs, for the most part dif- 
fers remarkably from the other bodies of this group, in 
the fact of its slight solubility in dilute acids and alkalies. 
It is likewise insoluble in water, alcohol, ether, the oils, 
and ill most ordinary solvents. It is hence prepared in 
a state of purity by acting upon vegetable tissues con- 
taining it, with successive solvents, until all other mat- 
ters are removed. 

The "skeletonized" leaves, fruit vessels, etc., which conii:>ose those 
beautiful objects called jtluintom bouquets, are commonly matic by dis- 
solving away the softer portions of fresh succulent plants by a hot solu- 
tion of caustic soda, and afterwards whitening the skeleton of fibers 
that remains by means of chloride of lime (bleaching powder). They 
are almost pure cellulose. 

Skeletons may also be prepared by steei^ing vegetable matters in a 
mixture of potassium chlorate and dilute nitric acid for a number of 
days. 

Exp. 22. — To 500 cubic centimeters* (or one pint) of nitric acid of dens- 
ity 1.1, add 30 grams (or one ounce) of pulverized potarjsium cliloralc, 
and dissolve the latter by agitation. Suspend in this mixture a num- 
ber of leaves, etc.,t and let them remain undisturbed, at a temperature 
not above G5° F., until they are perfectly whitened, which may recpiire 
from 10 to 20 days. The skeletons should be lloatiHl out from the 
solution on slips of paper, washed copiously in clear water, and dried 
under pressure l)etween folds of unsized jniper. 

The fd)ers of the whiter aiid softer kinds of wood are now much em- 
ployed in the fabrication of i)aj)er. For this purpose the wood is rasped 



* On subseqiient pages we shall make frequent use of some of the 
French decimal weights and measures, for the reasons that they are 
much more convenient than the p]nglish ones, and are now almost ex- 
clusively employed in all scientific treatises and investigations. For 
small weights, the (/nun, abbreviated gm. (equal to 15.} grains, nearly), 
is tlie cusfomai'y unit. The unit of measure by volume is the cubic cen- 
timeter, abbreviated c. c. (oO c. c. eiiiial oiu; tliiid ounce nenrly). Gram 
weighis and glass measures graduated into cubic centimeters are fur- 
nished by all dealers in cliemical apparatus. 

t Full-grown but not old leaves of the elm, maple, and maize, heads of 
unripe grain, slices of the stem aud joints of maize, etc., may be em- 
ployed to furnish skeletons that will prove valuable in the study of the 
structure of these organs. 



44 HOW CROPS GEOW. 

to a, coarse powder by macliinery, then heated with a weak soda lye, 
and finally bleached with chloride of lime. 

Though cellulose is insoluhle in, or but slightly affected 
by, weak or dilute acids and alkalies, it is altered and dis- 
solved by these agents, when they are concentrated or 
hot. The result of the action of strong acids and alka- 
lies is various, according to their kind and the degree of 
strength in which they are employed. 

Cellulose Nitrates. — Strong nitric acid transforms 
cellulose into various cellulose nitrates according to its 
concentration. In these bodies portions of the hydrogen 
and oxygen of cellulose are replaced by the atomic group 
(radicle), NO3. Cellulose hexanitrate, C12H14 (N03)60io, 
is employed as an explosive under the name gun cotton. 
The collodion employed in photography is a solution 
in ether of the penta- and tetranitrates, Ci2Hi5(N03)50io 
and Ci2Hic(N03)40io. Sodium hydroxide changes these 
cellulose nitrates into cellulose and sodium nitrate. 

Hot nitric acid of ordinary strength destroys cellulose 
by oxidizing it Avitli final formation of carbon dioxide 
gas and oxalic acid. 

Cellulose Sulphates. — When cold sulphuric acid 
acts on cellulose the latter may either remain apparently 
unaltered or swell up to a pasty mass, or finally dissolve 
to a clear li((uid, according to the strength of the acid, 
the time of its action, and the quality (density) of the 
cellulose. In excess of strong oil of vitriol, cellulose 
(cotton) gradually dissolves with formation of various 
ccUnluse sulphates, in which OH groups of the cellulose 
are replaced by SO4 of sulphuric acid. These sulphates 
are soluble in water and alcohol, and when boiled with 
water easily decompose, reproducing sulphuric acid, but 
not cellulose. Instead of the latter, dextrin and dextrose 
(grape sugar) a.]^pear. 

Soluble Cellulose, or Amyloid. — In a cooled mix- 
ture of oil of vitriol, with about ^ its volume of water, 



THE VOLATILE PART OF PLANTS. 45 

cellulose dissolves. On adding much water to the solu- 
tion there separates a white substance which has the same 
composition as cellulose, but is readily converted into 
dextrin by cold dilute acid. This form of cellulose as- 
sumes a fine blue color when put in contact with iodine- 
tincture and sulphuric acid. 

Exp. 23.— FiU a large test-tube first with water to tlie deptli of two or 
three inches. Tlien add gradually three times that bulk of oil of vitriol, 
and mix thoroughly. When well cooled i^our a part of the liquid on a 
slip of unsized paper in a saucer. After some time the pai^er is seen to 
swell up and partly dissolv^e. Now flow it with solution of iodine,* 
when these dissolved portions will assume a fine and intense blue color. 
This deportment is characteristic of cellulose, and may be employed 
for its recognition under the microscope. If the experiment be re- 
peated, using a larger proportion of acid, and allowing the action to 
continue for a considerably longer time, the substance producing the 
bkie color is itself destroyed, and addition of iodine has no effect. f Un- 
altered cellulose gives with iodine a ycUoiv color. 

Paper superficially converted into amyloid constitutes verfctable 
jyarchment, Avhich is tough and transhicent, much reseml>ling bladder, 
and very useful for various purx)oses, among others as a substitute for 
sausage "skins." 

Exp. 24.— Into the remainder of the cold acid of Exp. 23 dip a strii? of 
unsized paper, and let it remain for about 15 seconds ; then remove, and 
rinse it copiously in water. Lastly, soak some minutes in water, to 
which a little ammonia is added, and wash again with pure water. 
Tiiese washings are for the purpose of removing the acid. The success 
of this process for obtaining vegetable parchment depends upon the 
proper strength of the acid, and the time of immersion. If need be, 
repeat, varying these conditions slightly, until the result is obtained. 

The denser and more impure forms of cellulose, as they 
occur in wood and straw, are slowly acted upon by chem- 
ical agents, and are not easily digestible by most animals ; 
but the cellulose of young and succulent stems, leaves, 
and fruits is digestible to a large extent, especially by 
animals wliich naturally feed on herbage, and therefore 
cellulose is ranked among the nutritive ingredients of 
cattle-food. 

Chemical composition of cellulose. — This body is acom- 



* Dissolve a fragment of iodine as large as a wheat kernel in 20 c. c. of 
alcohol, and add 100 c. c. of water to the soliition. 

t According to Grouven, cellulose pre]iared from rye straw (and im- 
pure ?) requires several hours' action of sulphuric acid before it will 
strike a blue color with iodine (2ter Salzmilnder Bericht, p. 467). 



40 HOW CROPS GROW. 

pound of the three elements, carbon, oxygen, and hydro- 
gen. Analyses of it, as prei)ared from a multitude of 
sources, demonstrate that its composition is expressed by 
the formula (Cc Hio Or;)n. The value of n in this form- 
ula is not certainly known, but is at least two, and the 
formula Ci-.tlooOio is very commonly adopted. In 100 
parts it contains 

Carbon 44.44 

HyUro^'eii 0.17 

Oxygen 4"J.3t) 

100.00 

Modes of estimatinr/ ceUulose. — In statements of the composition of 
plants, tlie terms fiber, iroody fiber, and crude eeUtdose are often met 
with. These are apijlied to more or less imijnre cellulose, which is ob- 
tained as a residue after removing other matters, as far as possible, by 
aliernate treatment with dilute acids and alkalies. The methods are 
confessedly imperfect, because cellulose itself is dissolved to some ex- 
tent, and a portion of other matters often remains unattacked. 

The method of Hcnneberg, usually adopted ( 7\s. ,SY.,YI, 497), is as follows : 
3 grams of the finely tlivided substance are boiletl for half an hour wilh 
200 cubic centimeters of dilute sulphuric acid (containing \\ per cent of 
oil of vitriol), and, after the substance has settled, the acid liquid is 
lioured oiT. The residue is boiled again for half an hour with 200 c. c. of 
dilute potasli lye (containing 1^ per cent of dry caustic potash), and, after 
removing the alkaline Uquid, it is boiled twice with Avater as before. 
What remains is brought upon a filter, and washed witli Avater, then 
with alcohol, and, lastly, with ether, as long as these solvents take 
up anything. This crude cellulose contains ash and nitrogen, for which 
corrections must be made. The nitrogen is assumed to belong to some 
albununoid, and from its quantity the amount of the latter is calcu- 
lated; (seep. Ib3). 

Even with tliese corrections, tlie (piantity of cellulose is not obtained 
with I'ntire accuracy, as is usually indicated by its ai)|)earance and its 
composition. While the crude cellulose thus pri'pared f rom the])ea is 
perfectly wlule, that from wheat bran is brown, and that from rai>e- 
cake is almost black in color, from impurities that cannot be removed 
by this melliod. 

(Jrouven gives the following analyses of two samples of crude cellu- 
lose obtained by a method essentially the same as we have described. 
[;Zter Sahitiundrr Bericht, \). 45G.) 

liye-strair fiber. F/ax fiber. 

Water 8.65 5.40 

Ash 2.05 1.14 

N 0.15 0.15 

C 42.47 38.36 

H 6.04 5.89 

40.04 48.95 

100.00 lOO.OO 

On deducting water and ash, and making proper correction for the 



THE VOLATILE PART OF PLANTS. 47 



nilrogon, tlio. above samples, tosether -with one of wlicat-straw fiber, 
analyzed by Henneberg, exhibit the following composition, compared 
with pure cellulose. 

Rye-straw fiber. Flax fiber. Wlieat-straiv fiber. Pure cellulose. 

C 47.5 41.0 45.4 44.4 

II (;.s (5.4 6.3 ().- 

(>."■. 45.7 52.(i 48.3 4i).4 



lOO.U 100.0 100.0 100.0 

Fr. Schulze has proposed (1857) another method for estimating cellu- 
lose, which, though troublesome, is in most cases more correct than the 
one already described. Kiihn, Aronstein, and H. Schulze {Heiuicbertfs 
Jonraal fur Landalrthschaft, 18GG, pp. 289 to 297) have api)lied this 
method in the following manner : One part of the dry pulverized sub- 
stance (2 to 4 grams), which has been previously extracted with water, 
alcoliol, and ether, is placed in a glass-stoppered bottle, with 0.8 part 
of pi)tassium chlorate and 12 parts of nitric acid of specific gravity 1.10, 
and digested at a temperature not exceeding 05"^ F. for 14 days. At the 
expiration of this time, the contents of the bottle arc mixed with some 
water, broiight upon a filter, and washed, firstly, with cold and after- 
wards with hot water. When all the acid and soluble matters have 
been washed out, the contents of the filter arc emptied into a beaker, 
and heated to 105° F. for about 45 minutes with weak ammonia (1 part 
commei'cial ammonia to 50 pai'ts of water); the substance is then 
brought ui^on a weighed filter, and washed, first, with dilute ammonia, 
as long as this passes off colored, then with cold and hot water, then 
witli alcohol, and, finally, with ether. The substance remaining con- 
tains a small quantity of ash and nitrogen, for which corrections must 
be made. The fiber is, however, purer than that i^rocurod by the other 
method, and the writers named obtaincnl a somewhat larger quant-'ty, 
l)y \ to 1^ 2'^'' ('^>i^- The results ap]icar to vary but about one jtrr rent 
from the truth. The observations of Ki'mig (Vs. St. 10), and of IIolTmeis- 
tcr (Vs. St. 33, 155), show much larger dilTerences in favor of Fr. Schulze's 
motliod. 

Hugo Miiller (Die Pflanzenfaser, p. 27) has described a method of ob- 
taining cellulose from those materials which are employed in paper- 
making, which is based on the prolonged iise of weak aqueous solu- 
tion of bromine. 

Trials made on hay and Indian-corn fodder Avith this method by Dr. 
Osborne, at the aiithor's suggestion, gave results widely at vn,riance 
with those obtained by Henneberg's method. 

The average proportions of cellulose foiiiid in various 
vegetable matters, in the usual or air-dry state, are as fol- 
lows : 

AMOUNT OF CELLITLOSE IN PLANTS. 

Per cent. Per cent 

Potato tuber 1.1 Red clover i|>lant in flower — 10 

AVheat kernel 3.0 " " hav 34 

Wheat meal 0.7 Timothy 23 

Maize kernel 5.5 Maize cobs 38 

Barley " 8.0 Oat straw 40 

Oat " 10.3 Wheat" 48 

Buckwheat kernel 15.0 Rye " 54 



48 now CHOPS GROW. 

Starch (CeHioOs)!! is of very general occurrence in 
plants. The cells of the seeds of wheat, corn, and all 
other grains, and the tubers of the potato, contain this 
familiar body in great abundance. It occurs also in the 
wood of all forest trees, especially in autumn and winter. 
It accumulates in extraordinary (juantity in the pith of 
some plants, as in the Sago-palm {Sag us Eiimphii), of 
the Malay Iclands, a single tree of which may yield 800 
pounds. The onion, and various plants of the lily tribe, 
are said to be entirely destitute of starch. 

The preparation of starch from the potato is very sim- 
ple. The jiotato tuber contains about 70 per cent, water, 
24 per cent starch, and 1 per cent of celhdose, while the 
remaining 5 per cent consist mostly of matters which 
are easily soluble in water. By grating, the potatoes are 
reduced to a pulp ; the cells are thus broken and the 
starch-grains set at liberty. The pulp is agitated on a 
fine sieve, in a stream of water. The washings run off 
milky from suspended starch, while the cell-tissue is re- 
tained by the sieve. The milky liquid is allowed to rest 
in vats until the starch is deposited. Tiie water is then 
poured off, and the starch is collected and dried. 

Wheat-starch may be obtained by allowing wheaten 
flour mixed with water to ferment for several weeks. In 
this process the gluten, etc., are converted into soluble 
matters, which are removed by washing, from the unal- 
tered starch. 

Starch is now most largely manufactured from maize. 
A dilute solution of caustic soda is used to dissolve the 
albuminoids (see p, 87). The starch and bran remaining 
are separated by diffusing both in water, when the bran 
rapidly settles, and the water, being run off* at the proper 
time, deposits nearly pure starch, the corn-starch of com- 
merce. 

Starch is prepared by similar methods from rice, horse- 
chestnuts, and various other plants. 



THE VOLATILE PART OF PLAINTS. 



49 



ArTOW-roof is starch obtained by grating and washing 
the root-sprouts of Maranta Indica, and M. ar andinacGa, 
plants native to the Eact and West Indies. 

Exp. 25.— Reduce a clean potato to pulp by means uf a tin grater. Tie 
up the pulp in a iiiece of not too fine muslin, and squeeze it repeatedly 
in a cpiart or more of water. Tlie starch grains thus pass the meshes of 
the cloth, while the cellulose is retained. Let the liquid stand until 
the starch settles, pour off the water, and dry the residue. 

Starch, as usually seen, is either a white powder which 
consists of minute, rounded grains, and hence has a 
slightly harsh feel, or occurs in 5 or (3-sided columnar 
masses which readily crush to a powder. Columnar 
starch acquires that shape by rapid drying of the wet 
substance. When observed under a powerful magnifier, 
the starch-grains often present characteristic forms and 
dimensions. 

In potato-starch tbey are Qgg or kid noy-sh aped, and 
are distinctly marked with curved lines or ridges, which 




& © 



surround a point or eye ; a, Fig. 12. Wheat-starch con- 
sists of grains shaped like a thick burning-glass, or spec- 
tacle-lens, having a cavity in the centre, h. Oat-starch 
is made up of compound grains, which are easily crushed 
into smaller granules, c. In maize and rice the grains 
are usually so densely packed in the cells as to present an 
angular (six-sided) outline, as in d. The starch of the 
bean and pea has the appearance of e. The minute 
4 



50 now c:iops guow. 

starch-grains of tlic parsnip arc represented at /, and 
those of the beet at (j. 

The grains of potato-starcli are among the laj-gest, be- 
ing often ^Jg of an ii]ch in diameter ; wlieat-starcli 
grains are about xoVo t>f an inch ; those of rice, goVo ^^ 
an inch, while those of the beet-root are still smaller. 

The starch-grains have an organized structure, plainly 
seen in those from the potato, which are marked with 
curved lines or ridges surrounding a point or eye ; a, Fig. 
12. When a starch-grain is heated cautiously, it swells 
and exfoliates into a series of more or less distinct L-iyors. 

Starch, when air-dry, cont lins a considerable amount of 
water, which may range from 12 to 23 per cont. Most of 
this water escapes readily when starch is dried at 212'^, 
but a temperature of 230° F. is needful to expel it com- 
pletely. Starch, thus dried, has the same composition 
in 100 parts as cellulose, viz. : 

Carbon 44.44 

Hydrogen C.17 

Oxygen 40.39 

100.00 

Starch-grains are unacted u]ion by cold v/ater, unless 
broken (see Exp. 20), and (piickly settle from suspension 
in it, having a specific gravity of 1.5. 

lodiw-Tcst for Starch. — The chemist is usually able to 
recognize starch with the greatest ease and certainty by 
its peculiar deportment towards iodhie, which, when dis- 
solved in water or alcohol and brought in contact with 
starch-grains, most commonly gives them a beautiful 
l)lue or violet color. This test may be used even in 
microscopic observations with the utmost facility. Some 
kinds of starch-grains are, however, colored red, some 
yellow, and a few brown, probably because of the pres- 
ence of other substances. 

Exp. 2G.— Shake togetlier in a test-tube 30 c. c. of water and starch 
of the buUv of a kernel of maize. Add solution of iodine drop by drop, 
agitating until a faint purplish color appears. Pour off half tlie liquid 



THE VOLATILE TAI.T OF PLAXTS. 51 

into another test-tube, and add at once to it one-fourth its hulk of 
iodine solution. The latter portion becomes inlensely blue by trans- 
mitted, or almost black by reilected, ligiit. On standinj^, observe that 
in the first case, where starch in-eponderates, it settles to tlie bottom, 
leaving a colorless liquid, vsrliicli shows tlie insolubility of starch in 
cold water ; the starch itself has a purple or red tint. In the 'case 
iadine was used in excess, the deposited starch is blue-black. 

By the prolonged action of dry heat, hot watei, acids, 
or alkalies, starch is converted first into aniidulin, then 
into dextrin, and finally into the sugars maltose and dex- 
trose, as will be presently noticed. 

Similar transformations are accomplisiied by the action 
of living yeast, and of the so-called diastase of germinat- 
ing seeds. 

The saliva of man and plant-eating animals likewise 
disintegrates the starch-grains and mostly dissolves the 
starcli by converting it into maltose (sLigar). It is much 
more promptly converted into sugar by tlie liquids of the 
large intesti riO. It is thus digested when eaten by ani- 
mals. Starch is, in fact, one of the most important 
ingredients of the food of man and domestic animals. 

The starch-grains are not homogeneous. After pro- 
longed action of saliva, hot water, or of dilute acids on 
starch-grains, an undissolved residue remains whicli De- 
Saussure (1819) regarded as nearly related to ccllulo-^e. 
This residue is not changed by boiling water, but, under 
prolonged action of diiutc acids, it finally dissolves. 
With iodine, after treatment Vvdth strong sulphuric acid, 
it gives the blue color characteristic of cellulose. There- 
fore it is commonly termed starch-cellulase. 

Starch- cellulose amounts to 0.5 to 6 ]ier cent of the 
starch-grains, varying v»^ith the kind of starch and the 
nature and duration of the solvent action. Whether it 
be originally present or a resnlt of the treatment by 
acids, etc., is undecided. 

The chemical composition of starch-cellulose is identi- 
cal with that of the entire starch-grain, viz. : (Cfinio05)n. 

The starch-grains also contain a small proportion of 
amidulin, or soluble starch, presently to be noticed. 



52 now CROPS grow. 



Gelatinous Starch. When starch is heated to near boiling with 12 to 
15 times its weigiit of v/ater, tlie grains swell and burst, or exfoliate, 
the water is absorbed, and the whole forms a jelly. This is the starch- 
i:)aste used by the laundress for stilfening muslin. The starch is but 
very slightly dissolved by this treatment. On freezing gelatinous 
starch, the water belonging to it is separated as ice and on melting 
remains for the most part distinct. 

Exp. 27. — Place a bit of starch as large as a gi-ain of wheat in 30 c. c. 
of cold water and heat to boiling. The starch is converted into thin, 
translucent iiaste. That a portion is dissolved is shown by filtering 
through paper and adding to one-half of the filtrate a few drops of 
iodine solution, when a i^erfectly clear blue liquid is obtained. The 
delicacy of the reaction is shown by adding to 30 c. c. of water a little 
solution of iotline, and noting that iifew drojjs of the solution of starch 
suffice to make the large mass of liquid perceptibly blue. 

When starch-paste is dried, it forms a hard, horn-like mass. 

Tapioca and ,Sa(/o are starch, which, from being heated while still 
moist, is partially converted into starch-paste, and, on drying, acquires 
a more or less translucent aspect. Tapioca is obtained from the roots 
of various kinds of Ufanihof, cultivated in the AVest Indies and South 
America. Cassava is a preparation of the same str.rch, roasted. Sago 
is made in the islands of the East Indian Archipelago, from the pith of 
palms (Sar/its). It is granulated by forcing the paste through metallic 
sieves. Botli tapioca and sago are now imitated from maize starch. 

Next to water and cellulose, starch is the most abund- 
ant ingredient of agricultural plants. 

In the subjoined table are given the proportions of starch in certain 
vegetable products, as determined by Dr. Dragendorft". The qiumtities 
are, however, somewhat variable. Since the figures below mostly 
refer to air-dry substances, the proportions of hygroscopic waler foimd 
in the plants by Dragendortf are also given, the quantity of which, 
being changeable, must be taken into account in making any strict 
comparisons. 

AMOUNT OF STARCH IN PLANTS. 

Water. Starch. 

Per cent. Per cent. 

Wheat 13.2 59.5 

Wheat fiour 15.8 GS.7 

Rve 11.0 5'.).7 

Oiits 11.9 40.0 

Barley 11.5 57.5 

Timothy -seed 12.0 45.0 

Rice (hulled) 13.3 61.7 

Peas 5.0 37.3 

Beans (white) 1G.7 33.0 

Clover-seed 10.8 10.8 

Flaxseed 7.0 23.4 

Mustard-seed 8.5 9.9 

Colza-seed 5.8 8.0 

Teltow turnips* dry sid)stance 9.8 

Potatoes dry substance 02.5 



* A sweet and mealy turnip, grown on light soils, for table use. 



THE VOLATILE PART OF PLANTS. 53 

Starch is quantitatively estimated by various mctliods. 

1. In case of potatoes or cereal grains, it may be determined ronglily 
by direct mechanical separation. For this purpose 5 to 20 grams of the 
substance are reduced to fine division by grating (potatoes) or by sof- 
tening in warm water, and crushing in a mortar (grains). The pulp 
thus obtained is washed either upon a fine hair-sieve or in a bag of 
muslin, until the water runs off clear. The starch is allowed to settle, 
is dried, and weighed. The value of this method depends upon the care 
employed in the operations. The amount of starch falls out too low, 
because it is impossible to break open all the minute cells of the sub- 
stance analyzed. 

2. In many cases starch may be estimated with great precision by 
conversion into sugar. For this purpose Sachsse heats 3 grams of air- 
dry substance, contained in a flask with reflux condenser, in a boiling 
water bath for 3 hours, with 200 c. c. of Avater and 20 c. c. of a 25 per cent 
hydrochloric acid. After cooling, the acid is nearly neutralized with 
sodium hydroxide, and the dextrose into which the starch has been con- 
verted is determined by Allihn's method, described on p. 05. Winton, 
Report Ct. Ag. Exp. St., 1887, p. 132. 

3. For DragendorlFs method, see Henneberg's Journal, fur Land- 
wirthschaft, 18G2, p. 20G. 

Amidulin, or Soluble Starch. — A substance soluble 
in cold Welter appears to exist in small quantity in the in- 
terior of ordinary starch-grains. It is not extracted by 
cold water from the unbroken starch, as shown by Exp. 
26. On pulverizing starch-grains under cold water by 
rubbing in a mortar with sharp sand, the water, made 
clear by standing or filtration, gives with iodine tlie char- 
acteristic blue coloration. Exp. 27 shows that when 
starch is gelatin*::ed by hot water, as in making starch 
paste, a small quantity of starch goes into actual solu- 
tion. 

Ordinary insoluble starch may be largely converted 
into soluble starch by moderate heating, either for a long 
time to the temperature of boiling water or for a short 
space to 375° F. Maschke obtained a perfectly clear solu- 
tion of potato-starch by heating it with 30 times its bulk 
of water in a sealed glass tube kept immersed for 8 days 
in boiling water. Zulkowski reached the same result by 
heating potato-starch (1 part) with commercial glycerine 
(16 parts). In this case tlie starch at first swells and 
the mixture acquires a pasty consistence^ but, when the 



54 novv' CROPS grow. 

temperature rises to 375° F., the starch dissolves to a 
nearly clear thin liquid. 

Amiduliu also ai)pears to be the first product of the 
action of diastase (the ferment of sprouting seeds) on 
starch and doubtless exists in malt. 

SoUible starch is colored blue by iodine and is thrown 
down from its solution in water, or glycerine, by addition 
of strong alcohol. It redissolves in water or weak alco- 
hol. Its concentrated aqueous solutions gelatinize on 
keeping and the jelly is no longer soluble in water. 
Dihite solutions when evaporated leave a transparent 
residue tluit is insoluble in water. 

On boiling together diluted sulphuric acid and starch 
the latter shortly dissolves, and if as soon as solution has 
taken place, the acid be neutralized with carbonate of 
lime and removed by filtration, soluble starch remains 
dissolved. (Schulze's Amiduliu.) 

Amylodcxtrin. NageU has described as Amylodextrin I and Amylo- 
dextrin II, two substances that result from tlic action of moderately 
strong acids on potato-starch at common temperatures. The starch 
when soaked for many weeks in 12% hydrochloric acid remains nearly 
iinchanji-ed in appearance, but the interior parts of the grains grad- 
ually dissolve out, being changed into amylodextrin II, which clo:-.ely 
resemliles and is probably itlentical with amiduliu. 

The starcli-grains that remain unchanged in outward apiiearance. if 
tested with iodine solution from time to time, are at hist colored l)hie, 
but after some days tlieytakeon a violet tinge and after jirolouged 
action of the acid are made red and finally yellow by iodine. The grains, 
which are now but empty shells, may be freed from acid by washing 
with cold water, and then, if heated to boiling with pure water, they 
readily dissolve to a clear solution (amylodextrin I), from which Nagell, 
by freezing and by evaporation, obtained crystalline disks. These 
bodies, when dry, have the same composition as cellulose, starch, and 
amidulin. 

Dextrin (C0II10O5) was formerly tliought to occur 
dissolved in the sap of all plants. Accor ling to Vo'i 
Bibra's investigations, the substance existing in bread- 
grains, which earber experimenters believed to be dex- 
trin, is for the most part girrn. Busse, who examined 
various young cereal plants and seeds, and potato tu])ei's, 
for dextrin, found it only in old potatoes and young 



THE VOLATILE PART OF PLANTS. 55 

wiiciit phiiitL:, and there in very small quantity. Accord- 
ing' to Meitjsl, the soy bean contains JO per cent oi' dex- 
trin. 

Dextrin is easily prepared artificially by the trans- 
formation of starch, or, rather, of amidnlin derived from 
starch, and its interest to us is chiefly due tj this fact. 
When starch is exposed some hours to the heat of an 
oven, or for 30 miiiut3S to the temperature of 415° E., 
the grains swell, burst open, nnd are gradually converted 
into a light-brown substance, which dissolves readily in 
water, forming a clear, gummy solution. This is dex- 
trin, and thus prepared it is largely used in the arts, 
especially in calico-printing, as a cheap substitute for 
gum arable. In the baking of bread it is formed from 
the starcli of the flour, and often constitutes ten percent 
of the loaf. The glazing on the crust of bread, or upon 
biscuits that have been steamed, is chielly due to a coat- 
ing of dextrin. Dextrin is thus an important ingredient 
of those kinds of food which are ])rcj)ared from the 
starchy grains by cooking. 

Commercial dextrin appears either in translucent 
brown masses or as a yellowish-white powder. On ad- 
dition of cold water, the dextrin readily dissolves, leaving 
belli ud a jiortion of unaltered starch. When the solu- 
tion is mixed with strong alcohol, the dextrin separates 
in white flocks. With iodine, solution of commercial 
dextrin gives a fine purplish-red color. 

There are doubi^less several distinct dextrins scarcely dis- 
tino'uishable except by the ditferent degrees to which they 
affect polarized light or by various chemical de[)ortnient 
(reducing effect on alkaline copper solutions). They are 
characterized as erythrodextrins, which give with iodine 
a red. color, and achroodextrins, which give no color with 
iodine. Investigators do not agree as to the precise num- 
ber of dextrins that result from the transformaticn of 
starch. 



56 now CROPS Gitow. 

Exp. 28. — Cautioiisly heat a spoonful of iiowdered starch in a porce- 
lain dish, with constant stirring so that it may not burn, lor the si)ace 
of five minutes ; it acquires a yellow, and later, a brown color. Now 
add thrice i^s bulk of water, and heat nearly to boiling. Observe that 
a slimy solution is formed. I'our it upon a filter; the liquid tliat runs 
through contains dextrin. To a portion add tAvice its bulk of alcohol ; 
dextrin is precipitated. To another portion, add solution of iodine; 
this shows the presence of dissolved but unaltered starch. To a 
third i:)ortion of the filtrate add one drop of strong sulphuric acid and 
boil, a few minutes. Test with iodine, which, as soon as all starch is 
transformed, will give a red instead of a blue color. 

Not only heat but likewise acids and ferments produce 
dextrins from starch and, according to some authors, 
from cellulose. In the sprouting of seeds, dextrin is 
abundantly formed from starch and hence is an ingre- 
dient of malt liquors. 

The agencies that convert starch into the dextrins easily 
transform the dextrins into sugars (maltose or dextrose), 
as will be presently noticed. 

The chemical composition of dry dextrin is identical 
with that of dry cellulose, starch, and amidulin. 

Inulin, C36H62O3C, closely resembles starch in many 
points, and appears to replace that body in the roots of 
the American artichoke,* elecampane, dahlia, dandelion, 
chicory, and other plants of the same natural family 
(composite). It may be obtained in the form of minute 
white grains, which dissolve easily in hot water, and sep- 
arate again as the water cools. According to Bouchardat, 
the juice of the dahlia tuber, expressed in Avinter, becomes 
a semi-solid white mass after reposing some hours, from 
the separation of 8 per cent of inulin. 

Inulin, when pure, gives no coloration with iodine. It 
may be recognized in plants, where it occurs as a solu- 
tion, usually of the consistence of a thin oil, by soaking 
a slice of the plant in strong alcohol. Inulin is insolu- 
ble in this liquid, and under its influence shortly separ- 



* Helianthns tubcrosns, commonly known as Jerusalem artichoke, and 
cultivated in Europe under the name topinambour, is a native of the 
Northern Mississippi States. 



THE VOLATILE PART OF PLANTS. 57 

afces as a solid in the form of s})herical grannies, which 
may be identified with the aid of the microscope, and 
have an evident crystalline structure. 

■ When long heated with water it is slowly but complete- 
ly converted into a kind of sugar (levulose); hot dilute 
acids accomj^lish the same transformation in a short 
time. It is digested by animals, and doubtless has the 
same value for food as starch. 

In chemical composition, innlin, dried at 212°, differs 
from cellulose and starch by containing for six times 
CgHioOs, the elements of an additional molecule of water ; 
CgoHcaOgs = 6 C0II10O5 + II2O Kiliani. 

Levulin (CeHioO^jn coexists with inulin in the mature 
or frozen tubers of the artichoke, dahlia, etc., and, accord- 
ing to Muentz, is found in unripe rye-grain. It is a highly 
soluble, tasteless, gum -like substance resembling dextrin, 
but without effect on polarized light. It appears to be 
formed from inulin when the latter is long heated with 
water at the boiling point, or when the tubers contain- 
ing inulin sprout. Dilute acids readily tnuisform it into 
levulose, as they convert dextrin into dextrose. 

^tLYCOGEN (C6Hio05)n exists in the blood and mus- 
cles of animals in small quantity, and abundantly in the 
liver, especially soon after hearty eating. It h obtained 
by boiling minced fresh livers with water, or weak potash 
solution, and adding alcohol to the filtered liquid. It is 
a white powder which, with water, makes an opalescent 
solution. It is colored wine-red by iodine. Boiling di- 
lute sulphuric acid converts it into dextrose. With caliva, 
it is said to yield dextrin, maltose and dextrose. Accord- 
ing to late observations, glycogen occurs in the vegetable 
kingdom, having been identified in various fungi and in 
plants of the flax and the potato families. 

The Gums and Pectin Bodies. — A number of 
bodies exist in the vegetable kingdom, which, from the 
similarity of their properties, have received the commou 



58 



HOW CliOr.J GROW. 



designation of o'ums. Tlio bost kiiuv/ii arc Gum Arabic, 
the gums of the Peach, Cherry and Pluin, Gum Traga- 
canth and Bassora Gum, Agar-Agar ;uid the Mucilages 
of various roots, viz,, of mallow and comfrey ; and of 
certain seeds, as those of llax and quince. 

Gum Arabic exudes from the stems of various species 
of acacia that grow in the tropical countries of the East, 
esj^ecialiy in Arabia and Egy})t. It occurs in tear-like, 
transparent, and, in its purest form, colorless masses. 
These dissolve easily in their ovv^n "weight of water, form- 
ing a viscid liquid, or mucilage, ^vhich is employed for 
causing adhesion between surfaces of paj)er, and for 
thickening colors in calico-printing. 

Gum Arabic is, however, commonly a mixture of at 
least two very similar gums, which are distinguished by 
their opposite effect on polarized light and by the diller- 
ent products which they yield when boiled with dilute 
acids. 

Che^'ry Gum. — The gum which frequently forms 
glassy masses on the bark of cherry, plum, aprice)t, peach 
and almond trees, is a mixture in variable proportions of 
two gums, one of which is apparently the same as occurs 
in gum arable, and is fully dissolved in cold water, while 
the other remains undissolved, but . 
swollen to a pasty mass or jelly. 

Giun TrcMjacantli, which comes ' 
to us from Persia and Siberia, has 
much similarity in its i)roi)erlies b 
to the insoluble part of cherry c\ 
gum, as it dissolves but slightly in ^ 
water and swells up to a paste or 
jelly. 

The so-called Vegdaldc m ucila'jes 
much resemble the insoluble part 
of cherry gum and are found in 
the seeds of flax, quince, lemon, and in various parts of 
many plants. 




OOOOI 




'f^^^C , 






-■■Dry 



W^-Lr 



11. i;j. 



THE VOLATILE PART OF PLANTS. 59 

Flax-seed mucilage is in^ociired by soaking unbroken flaxseed in cold 
water, witli frequent agitation, heating tlie liquid to boiling, strain- 
ing, and evaporating, until addition of alcohol separates tenacious 
threads from it. It is then precipitated by alcohol containing a little 
hydrochloric acid, and washed by the same mixture. On drying, it 
forms a horny, colorless, and friable mass. Fig. 13 represents a highly 
magnified section of the ripe llaxseed. The external cells, a, contain 
the dry mucilage. When soaked in water, the mucilage swells, bursts 
the cells, and exudes. 

The Pectin Bodies. — The flesh of beets, turnips, and 
similar roots, and of most unripe fruits, as apples, 
jDcaches, plums, and berries of various kinds, contain one 
or several bodies which are totally insoluble in water, but 
which, nnder the action of weak acids or alkaline solu- 
tions, become soluble and yield substances having gummy 
or gelatinous characters, that have been described under 
the names pectin, pectic acid, pectosic acid, metapectic 
acid, etc. Their true composition is, for the most j^art, 
not positively established. They are, however, closely 
related to the gums. The insoluble substance thus trans- 
formed into gum-like bodies, Fremy ian-vaQdi pecfose. 

The gums, as they occur naturally, are mostly mix- 
tures. By boiling with dilute sulphuric or hydrochloric 
acid they are transformed into sugars. 

In the present state of knowledge it appears probable 
that the common gumc, for the most part, consist of a 
few chemically distinct bodies, some of which have been 
distinguished more or less explicitly by such names as 
Arabin, Metarabin, Pararabin, Galactin, Paragalactin, 
etc. 

Arabin, or Arabic Acid, is obtained from some va- 
rieties of Gum Arabic* by mixing their aqueous solution 
with acetic acid and alcohol. It is best prepared from 
sugar-beet pulp, out of which the juice has been ex- 
pressed, by heating with milk of lime ; the pulp is 
thereby broken down, and to a large extent dissolves. 



* Tliose sorts of commercial Gum Arabic which deviate the plane of 
polarization of light to the left contaiji arabin in largest proportion. 



60 now CROPS GROW. 

The liquid, after sepaniting excess of lime and adding 
acetic acid, is mixed with alcohol, whereupon arabiii is 
precipitated. Arabin, thus prepared, is a milk-white 
mass which, while still moist, readily dissolves in water 
to a mucilage. It strongly reddens blue litmus and ex- 
pels carbonic acid from carbonates. When dried at 212° 
arabin becomes transparent and has the composition 
C12H22O11. Dried at 230° it becomes (by loss of a mole- 
cule of water) CiaHooOio, or 2 C6nio05. 

Arabin forms compounds with various metals. Those 
with an idkali, lime, or magnesia as base are soluble in 
water. Gum arable, when burned, leaves 3 to 4 percent 
of ash, clii:'fiy carbonates of potassium, calcium and mag- 
nesium. Ar:;bic acid, obtained by Fremy from beets by 
the foregoing method, but not in a state of purity, v/as 
described by him as ^'metapectic acid." To Scheibler 
we owe the proof of its identity Avith the arabin of gum 
arabic. 

Metarabin. — When arabin is dried and kept at 212° 
for some time, it becomes a transparent mass which is no 
longer freely soluble in water, but in contact therewith 
swells up to a gelatinous mass. This is designated 
metarabin by (""clieibler. It is dissolved by alkalies, and 
thus converted into arabates, from which ara])in m.ay 1)0 
again obtained. 

The body named idararabin by Reichardt, obtained 
from beet and carrot ]mlp by treatment with dilute hy- 
drochloric acid, is related to or the same as metarabin. 
Fremy's '^•'pectin," obtained by similar treatment from 
beets, IS probably impure metarabin. 

Exr. 34.— Uoduco several wlute turnii^s or beets to pulp by grating. 
Inclose the pulp in a piece of muslin, and wash by squeezing in water 
until all soluble matters are removed, or until the water comes off 
nearly tasteless. Bring the washed pulp into a glass vessel, Avith 
enough dUute hydrochloric acidd part by Imlkof commercial muriatic 
acid to 15 parts of water) to saturate the mass, and let it stand 4s hours. 
Squeeze the acid liquid, filter it, and add alcohol, when "pectin" will 
sejiarate. 



THE VOLATILE PART OF PLANTS. 61 

Ifc may be that metarabiii is identical with the *^pec- 
tose " of the sugar beet, since both yield arabin under the 
influence of alkalies. It is evident that the composition 
found for dried arabin properly belongs to metarabin, and 
it is probable that arabin consists of metarabin C12H22O11 
plus one or several molecules of water, and that metara- 
bin is an cuthydride of arabin. 

Arabin and metarabin, when heated with dilute sul- 
phuric aciJ, are converted into a crystallizable sugar 
called arabinose, O5H10O5. The gums that exude from 
the stems of cherry, plum and peach trees appear to con- 
sist chiefly of a mixture of freely soluble arjibates with 
insoluble metarabin. Gum Tragacanth is perhaps mostly 
metarabin. All these gums yield, by the action of hot 
dilute acids, the sugar arabinose. 

Galactin, CgHiqOs, discovered by Miintz in the seeds 
of alfalfa [ind found in other legumes, has the appearance, 
solubility in water and general properties of arabin, and 
is probably the right-polarizing ingredient of gum arable. 
Boiled with dilute acids it is converted into the susfar 
galactose, OellisOe. 

Paragalactin, CcHioOs. — In the seeds of the yellow 
lupin exists up to 20 per cent of a body that is insoluble 
in water, but dissolves by warming with alkali solutions, 
and when heated with dilute acids yields galactose. Ac- 
cording to Steiger it probably has the composition CcHioOs. 
Maxwell has shown it to exist in other leguminous- seeds, 
viz., the pea, horse-bean (Faba vulgaris) and vetch. 

In the '^ Chinese moss," an article of food prejoared in 
China from sea-weeds, and in the similar G^um asrar or 
'S^egetable gelatine" of Jajian, exists a substance which 
is insoluble in cold water, but with that liquid swells up 
to a bulky jelly, and yields galactose when heated with 
dilute acids. This corresponds to metarabin. 

Xylin, or Wood Gum. — 'i'he wood of many decidu- 
ous trees, the vegetable ivory nut, the cob of Indian 



62 HOW CROPS GROW. 

corn and barley linsks, contain 6 to 20 per cent of a sub- 
stance insoluble in cold water, but readily taken up in 
cold solution of caustic soda. On adding to the solution 
an acid, and afterwards alcohol, a bulky Avhite substance 
separates, which maybe obtained dry as a white powder 
or a translucent gum-like mass. It dissolves very slightly 
in boiling water, yielding an opalescent solution. The 
composition of this substance was found by Thomsen to 
be CcHioOs. ^ 

Xylin differs from ^^ararabin and pectose in not being 
soluble in milk of lime. It is converted by boiling with 
dilute sulphuric acid into a crystallizable sugar, xylose, 
whose properties have boon but little investigated. 

Flax-seed Mucilage, OcHioOs, resembles metarabin, 
but by action of hot dilute acids is resolved into cellulose 
and a gum, which latter is further transformed into dex- 
trose. The yield of cellulose is about four per cent. 

Quince-Seed Mucilage appears to be a compound of 
cellulose and a body like arabin. On boiling with dilute 
sulphuric acid it yields nearly one-third its weight of cel- 
lulose, together with a soluble gum and a sugar, the last 
being a result of the alteration of the gum. The sugar 
is similar to arabinose. 

The Sulnhh Gums in Brcad-r/rains. — In the bread- 
grains, freely soluble gums occur often in considerable 
proportion. 

TABLE OF THE PROPORTIONS (percent.) OF GUM* IN VARIOUS AIR-DRY 
GRAINS OR MILL PRODUCTS. 

{According to Voii Bibra, Die Getreldearten nnd das Brod.) 



Wheat kernel 4.50 

Wheat flour, superfine 6.25 

SiJelt flour ( TrUicmti speltci) . . 2.48 

Wlieat bran 8.85 

Spelt bran 12.52 

Rye kernel 4.10 



Barley flonr 6.33 

Barley bran 6.83 

Oat meal 3.C0 

Riee flour 2.00 

iWllet flour 10.60 

Maize meal 3.05 



Rye flour 7.25 j Buckwheat flour 2.85 

Rye bran 10.40 I 



* The " si^m " in the above table (which dates from 1850), includes per- 
haps solubh', starch and dextrin iai some, if not all cases, antl, accord- 
intj; to O'Sullivan, barley, wheat and rye contain two distinct left-pol- 
ariziiiii" Ljunis, wliicli he terms <i-(nn i/fdu :u\il h-(nnijl<m. These occur in 
bailey io tlic extent of 2.3 per cent. Jiy action of acids tliey yield 
(^lextrose. 



THE VOLATILE PART OF PLANTS. 68 

The experiments of GrouYcn show that gnm arable is 
digestible by domestic animals. There is httle reason to 
doubt that all the gums are digestible and serviceable as 
ingredients of the food of animals. 

1). The Glucoses, CcHioOe (or C5H10O5), are a class of 
sugars having similar or identical composition, bat dif- 
fering from each other in solubility,, sweetness, melting 
point, crystal-form and action on polarized light. 

The ghicoses, with one exception, contain in 100 parts : 

Carbon 40.00 

Hydrogen C.G7 

Oxygen 53.33 

100.00 

Levulose, or Fruit Sugar (Fructose), GcITioOs, 
exists mixed with other sugars in sweet fruits, honey and 
molasses. Inulin and Icvulin are converted into this 
sugar by long boiling with dilute acids, or v/ith water 
alone. When pure, it forms colorless crystrJs, which 
melt at 203°, but is usually obtained as a syrup. Its 
svv^cetness is equal to that of saccharose. 

Dextrose or Grape Sugar, Celli^Oc, naturally oc- 
curs associated with levulose in the juices of plants and 
in honey. Granules of dextrose separate from the jaice 
of the grape on drying, as may be seen in old *^ candied" 
raisins. Honey often granulates, or candies, on long- 
keeping, from the crystallization of its dextrose. 

Dextrose is formed from starch and dextrin by the ac- 
tion of hot dilute acids, in the same way that levulose is 
produced from inulin. In the pure state it exists as 
minute, colorless crystals, and is, weight for weight, bat 
two-thirds as sweet as saccharose or cane-sugar. It fuses 
at 295°. 

Dextrose unites chemicany to water. Hydrated glucose, Ci;Hi20,,Tl2fi, 
occurs in commerce in an impure state as a crystaUine mass, which 
becomes doughy at a sUglxtly elevated temi^erature. This hydrate 
loses its crystal-water at 212"^. 

Dissolyed in vrater, dextrose yields a syrujo, which is 



C4 HOW CROPS GROW. 

thin, and destitute of tlie ropiness of cane-sngar syrup. 
It does not crystallize (granulate) so readily as cane- 
sugar. 

Exp. 30.— Mix 100 c. c. of water with 00 drops of strong sulphuric acid, 
and heat to vigorous LoiUng in a glass flask. Stir 10 grams of starch 
with a little water, and pour the mixture into the hot liquid, drop by 
drop, so as not to interrupt the boiling. The starch dissolves, and passes 
successively into aniidulin, dextrin, and dextrose. Continue the ebul- 
lition for several hours, replacing the evaporated water from time to 
time. To remove the sulphuric acid, add to the liquid, which may be 
still milky from imi)urities in the starch, powdered chalk, xintil the sour 
taste disapi^ears ; filter from the calcium sulphate (gypsvim) that is 
formed, and evaporate the solution of dextrose* at a gentle heat to a 
syrupy consistence. On long standing it may crystallize or granulate. 

By this method is prepared the so-called grape-sugar, or starcli-sugar 
of commerce, which is added to grape-juice for making a stronger 
wine, and is also employed for preparing syrujis and imitating molasses. 
The syrups thus made from starch or corn are known in the trade as 
glucose.^ Imitation-molasses is a mixture of dextrose-syrup with some 
dextrin to make it " ropy." 

Even cellulose is convertible into dextrose by the pro- 
longed action of hot acids. If paper or cotton be first 
dissolved in strong sulphuric acid, and the solution 
diluted with water and boiled, the celhilose is readily 
transformed into dextrose. Sawdust has thus been made 
to yield an impure syrujo, suitable for the production of 
alcohol. 

In the formation of dextrose from cellulose, starch, amidulin and 
dextrin, the latter siibstances take uj) the elements of water as repre- 
sented by the equation 

Starch, etc. Water. Glucose. 

CoHioOg + lUO = CcHi^Oc 

In this process, 90 parts of starch, etc., yield 100 parts of dextrose. 

Trommcr's Copper test. — A characteristic test for dextrose and levu- 
lose is found in their deportment towards an alkaline solution of cop- 
per, which readily yields up oxygen to these sugars, the copper being 
reduced to yellow cuprous hydroxide or red ciiprous oxide. 

Exp. 31.— rrepare the copper test by dissolving together in 30 c. c. of 
warm water a pinch of sulphate of copper and one of tartaric acid; 
add to the liquid, solution of caustic potash until it acquires a slip- 



* If the boiling has been kept up but an hour or so, the dextrose will 
contain dextrin, as may be ascertainc:! by mixing a small portion of 
the still acid liquid with 5 times its bulk of strong alcoiiol, which will 
precipitate dextrin, but not dextrose. 

t Under the name nhiyose, the three sugars levulose, dextrose and 
maltose were ''ormerly confounded together, by chemists. 



THE VOLATILE PAET OF PLANTS. 65 

pery feel. Place in separate test tubes a few drops of solution of cane- 
sugar, a similar amount of the dextrin solution, obtained in Exi>, 28; 
of solution of dextrose, from raisins, or from Exp. 30 ; and of molasses ; 
add to each a little of the copper solution, and j)lace them in a vessel 
of hot water. Observe that the saccharose and dextrin suffer little or 
no alteration for a long time, while the dextrtjse and molasses shortly 
cause the separation of cuprous oxide. 

Exp. 32. — Heat to boiling a little white cane-sugar with 30 c. c. of 
water, and 3 drops of strong sulphuric acid, in a glass or porcelain dish, 
for 15 minutes, supplying the waste of water as needful, and test the 
liquid as in the last Exp. This treatment transforms saccharose into 
dextrose and levulose. 

Tlic qiiantltafive estimation, of the surjars and of starch is commonly 
based uijon the reaction just described. For this imrpose the alkaline 
copi>er solution is made of a known strength by dissolving a given 
weight of sulphate of copper, etc., in a given volume of water, and the 
dextrose or levulose, or a mixture of both, being likewise made to a 
known volume of solution, the latter is allowed to flow slowly from a 
graduated tube into a measured portion of warm copper solution, until 
the blue color is discharged. Saccharose is first converted into dex- 
trose and levulose, by heating with an acid, and then examined in the 
same manner. 

Starch is transformed into (Lextrose by heating with hydrochloric 
acid or warming with saliva. The quantity of sugar stands in definite 
relation to the amount of copper separated, when the experiment is 
carried out under certain conditions. See Allihn, Jour.filr Pr. Chemie, 
XXII, p. 52, 1880. 

Galactose, OeHiaOc, is formed by treating right- 
polarizing gum arabic, galaciin, or milk-sugar with 
dilute acids. It crystallizes, is sweet, melts at 289° and 
with nitric acid yields mucic acid (distinction from ara- 
binose, dextrose and levulose). 

Mannose (Seminose?) CgHioOg is a fermentable sugar 
prepared artiiicially by oxidation of mannite (see p. 74), 
and, according to E. Fischer, is probably identical with 
the Seminose found by Reiss as a product of the action 
of acids on a body existing in the seeds of coffee and in 
palm nut?. {Berichte. XXII, p. 365). 

Arabinose, C5H10O5, obtained from arabin (of left- 
polarizing gum arabic), and from cherry gum by action 
of hot dilute acids, appears in rhombic crystals. It is 
less sweet than cane sugar, and fuses at 320°. 

c. The Siicroses, CisHooOn, are sugars which, boiled with 
dilute acids, undergo chemical change by taking up the 
5 




66 HOW CROPS GROW. 

elements of water and are thereby resolved into glucoses. 
In this decomj^osition one molecule of sucrose usually 
yields either two molecules of one glucose or a molecule each 
of two glucoses, Oi,H,oOn + 11,0 = CoHioOc + C0H12O6. 

Saccharose, or Cane Sugar, CioIIooOn, so called 
because first and chiefly prepared from the 
sugar-cane, is the ordinary sugar of com- 
merce. When pure, it is a white solid, 
readily soluble in water, forming a color- Fig. u. 
less, ropy, and intensely sweet solution. It crystallizes 
in rhombic ]n-isms (Fig. 14), which are usually small, as 
in granulated sugar, but in the form of rock-candy may 
be found an inch or more in length. The crystallized 
sugar obtained largely from the sugar-beet, in Europe, 
and that furnished in the United States by the sugar- 
maple and sorghum, v/hen pure, are identical with cane- 
sugar. 

Saccharose also exists in the vernal juices of the wal- 
nut, birch, and other trees. It occurs in the stems of 
unripe maize, in the nectar of flowers, in fresh honey, iu 
parsnips, turnips, carrots, parsley, sweet jiotatoes, in the 
stems and roots of grasses, in the seeds of the pea and 
bean, and in a multitude of fruits. 

Exp. 29. — Heat cautiously a spoonful of white sugar until it melts (at 
35G° F.) to a clear yellow liquid. On rapid cooling, it gives a transpar- 
ent mass, known as barley sugar, wliicli is employed in confectionery. 
At a higher heat it turns hrown, froths, emits pungent vapors, and be- 
comes burnt sugar, or caramel, which is used for coloring soups, ale, etc. 

The quantity per cent of saccharose in the juice of various plants is 
given in the annexed table. It is, of course, variable, depending upon 
the variety of plant in case of cane, beet, and sorghum, as well as upon 
the stage of growth. 

SACCHAROSE IN PLANTS. 

Per cent. 

Sugar-cane, average 18 Peligot. 

Sugar-beet, " 10 

Sorghum 13 Collier. 

Maize, just flowered 3J LiUlersdorff. 

Sugar-maple, sap, average 2^ Liebig. 

Red maple, " " ^ " 



THE VOLATILE PART OF PLANTS. 07 

The composition of saccharose is the same as that of 
aiabin_, and it contains in 100 parts : 

Carbon 42.11 

Hydrogen (i.43 

Oxygen 51.46 

100.00 

Cane-sugar, by long boiling of its concentrated aqueous 
solution, and under the influence of hot dihite acids (Exp. 
32) and yeast, loses its property of ready crystallization, 
and is converted into levulose and dextrose. 

According to Dubrunfaut, a molecule of cane-sugar takes up the ele- 
ments of a molecule (5.2G per cent.) of water, yielding a mixture of 
equal parts of levulose and dextrose. This change is expressed in 
chemical symbols as follows : 

CioH,,0,i + H3O = C,H,20„ + C«H,30„ 
Cane-swjar. Water. Levulose. Dextrose. 

This alterability on heating its solutions occasions a 
loss of one-third to one-half of the saccharose that is 
really contained in cane-juice, Avhen this is evaporated in 
open pans, and is one reason why solid sugar is obtained 
from the sorghum in open-pan evaporation with sucli dif- 
ficulty. 

Molasses, sorghum syrup, and honey usually contain 
all three of these sugars. 

Honey-dew, that sometimes falls in viscid drops from 
the leaves of the lime and other trees, is essentially a mix- 
ture of the three sugars with some gum. The mannas of 
Syria and Kurdistan are of similar composition. 

Maltose, Ci2ri220ii.H20, is formed in the sprouting 
of seeds by the action of a ferment, called diastase, on 
starch. It is also prepared by treating starch or ,£:lycogen 
with saliva. In either case the starch (or glycoo-en) takes 
up the elements of water, 2 CcHioOs -|- HgO = C12H22O11. 
Maltose in crystallizing unites with another molecule of 
water, which it loses at 212°. Maltose, thus dried, 
attracts moisture with great avidity. 

Boiled with dilute acids one molecule of maltose yields 



08 now CROPS GROW. 

two molecules of dextrose, C12H22O11 + IIoO = 2 C6II12O6. 
Maltose is also produced when starch and doxtrin are 
heated with dilute acids, and thus appears to be an inter- 
mediate stage of their transformation into dextrose. 

Maltose is accordingly an ingredient of some commer- 
cial ^^grape-sugars" made from starch by boiling with 
dilnted sulphuric acid. 

Lactose, or Milk Sugar, CioHoeOn + HoO, is the 
sweet principle of the miik 01 animals. It is prepared 
for commerce by evaporating whey (milk from which 
casein and fat have been separated for making cheese). 
In a state of purity it forms transparent, colorless crys- 
tals, which crackle under the teeth, and are but slightly 
sweet to the taste. When dissolved to saturation in 
water, it forms a sweet but tliin syrup. Heated to 290° 
the crystals become water-free. 

Lactose is said to occur Avith cane-sugar in tlic sapo- 
dilla (fruit of Achras sapota) of tropical countries. 
Treatment with dilute sulphuric acid converts it into 
galactose and dextrose. 

C,2H2oO„ + H,0 = CoHjoOn + Cp,TT,,0,, 
Lactose. Water. Galactose. Dextrose. 

Raffinose, CigHsoOiG + 5 H2O (?), first discovered 
by Loiseau in beet-sugar molasses, was afterwards found 
by Berthelot in eucalyptus manna, by Lippmann in beet- 
root, and by Boehm & Kitthausen in cotton-seed. It 
crystallizes in fine needles, and is but slightly sweet. It 
begins to melt at 190° witli loss of crystal- water, which 
may be completely expelled at 212°. The anhydrous 
sugar fuses at 23G°. It is more soluble in water and has 
higher dextrorotatory power than cane-sugar. Heated 
with dilute acids it yields dextrose, levulose and galactose. 

Ci8H320ifi + 2 H,0 = 3 (C.HioOo). 

The Sugars in Bread- Grains. — The older observers 
assumed the presence of dextrose in the bread-grains. 



THE VOLATILE PART OF PLANTS. G9 

Thus, Yanqueliii fouod, or thought he found, 8.5% of 
this sugar in Odessa wheat. More recently, Peligot, 
Mitscherlich, and Stein deried the presence of any sugar 
in these grains. In his work on tlie Cereals and Bread, 
{Die Geireidcai'ten iind da^ Brod, 1860, p. 1G3), Von 
Bibra reinvestigated this question, and found in fresh- 
ground wheat, etc., a sugar having some of the charac- 
ters of saccharose, and others of dextrose and levulose. 
Marcker and Kobus, in 1882, report maltose (which was 
unknown to the earlier observers) in sound barley, and 
maltose and dextrose in sprouted barley. 

Von Bibra found in the flour of various grains the following quanti- 
ties of sugar : 

PROPOETIONS OF SUGAR IN AIR-DRY FLOUR, BRAN, AND MEAL. 

Per cent. 

Wheat flour 2.33 

Spelt flour 1.41 

Wheat bran 4.30 

Spelt bran 2.70 

Eye flour 3.40 

Rye bran 1.8G 

Barley meal 3.04 

Barley bran 1.1)0 

Oat nieal 2.11) 

Rice flour 0.30 

Millet flour 1.30 

Maize meal 3.71 

Buckwheat meal O.'Jl 

Glucosides. — There occur in the vegetable kingdom a 
large number of bodies, usually bitter in taste, which 
contain dextr;)se, or a similar sugar, chemically combined 
with other substances, or that yield it on decomposition. 
Scillcin, from willow bark ; ^^/^^i^riVZ^i;?, from the bark of 
the apple-tree root ; jalapiii, from jalap ; arscitUn, from 
the horse-chestnut, and amygdalin, in seeds of almond, 
j)each, plum, apple, cherry, and in cherry-laurel leaves, 
are of this kind. The sugar may be obtained from these 
so-called glucosides by heating with dilute acids. 

The seeds of mustard contain the glucoside myronic acid united to 
potassium. This, when the crushed seeds are wet with water, breaks 
up into dextrose, mustard-oil, and acid i^otasslum sulphate, as follows : 

Cio Hi, K N S, Oio = CcHi^Oe + C3 H^ N C S + K H S O4 
'She cambial juice of the conifers contains co?i(/criM, crystallizing in 



70 HOW CROPS GROW. 

brilliant needles, which yields dextrose and a resin by action of dilute 
acid, and by oxidation i^roduces vanillin, the llavoring principle of the 
vanilla bean. 

Mutual Transformations of the Carhhydrates. — One of 
the most remarkable facts in the history of this group of 
bodies is the facility with which its members undergo 
mntual conversion. Same of these changes have been 
already noticed, but we may appropriately review them 
here. 

a. Transformations in the plant. — In germinati on, the 
starch which is largely contained in seeds is converted 
into amidulin, dextrin, maltose and dextrose. It thus ac- 
quires solubility, and passes into the embryo to feed the 
young plant. Here these ara again solidified as cellulose, 
starch, or other organic principle, yielding, in fact, the 
chief part of the materials for the structure of the seed- 
ling. 

At spring-time, in cold climates, the starch stored up 
over winter in the new wood of miiiy trees, especially the 
maple, appears to be converted into the sugar which is 
found so abundantly in the sap, and this sugar, carried 
upwards to the buds, nourishes the young leaves, and is 
there transformed into cellulose, and into starch again. 

The sugar-beet root, when healthy, yields a juice con- 
taining 10 to 14 per cent, of saccharose, and is destitute 
of starch. Schacht has observed that, in a certain dis- 
eased state of the beet, its sugar is partially converted 
into starcli, grains of this substance making their appear- 
ance. {Wikla's Centralhlatt, 1863, II, p. 217.) 

In some years the sugar-beet yields a large amount of 
arabin, in others but little. 

The analysis of the cereal grains sometimes reveals the 
presence of dextrin, at others of sugar or gum. 

Thus, Stepf found no dextrin, but both gum and sugar in maize-meal 
{Jour, fur Prakt. Chcm., 76, p. 92); while Fresenius, in a more recent 
analysis (Vs. St., I, p. 180), obtained dextrin, but neither sugar nor gum. 
The sami>le of maize examined by Stepf contained 3.05 p. c. gum and 
3.71 p. c. sugar; that analyzed by Fresenius yielded 2.33 p. c. dextrin. 



THE VOLATILE PART OF PLANTS. 71 

MJircker & Kobiis made comparative analyses of well-cured and of 
sprouted barley, with the following results per cent: 

Sound. Grown. 

Starch 64.10 57.98 

Soluble starch 1.7G 1.17 

Dextrin. 1.10 0.00 

Dextrose 0.00 4.02 

Maltose 3.12 7.02 

The various gums are a result of the transformation of 
celluh)se, as Mohl first showed by microscopic study. 

h. In the animal, the substances we have been describ- 
ing also suffer transformation when employed as food. 
During the process of digestion, cellulose, so far as it is 
acted upon, starch, dextrin, and i)robably the gums, are 
all converted into dextrose or other sugars, and from 
these, in the liver especially, glycogen is formed. 

c. Many of these changes may also be produced apart 
from physiological agency, by the action of heat, acids, 
and ferments, operating singly or jointly. 

Cellulose and starch are converted, by boiling with a 
dilute acid, into amidulin, dextrin, maltose and dextrose. 
Cellulose and starch acted upon for some time by strong 
nitric acid give compounds from which dextrin may be 
separated. Cellulose nitrate sometimes yields gum (dex- 
trin) by its spontaneous decomposition. A kind of gum 
also appears in solutions of cane-sugar or in beet-juice, 
when they ferment under certain conditions. Inulin and 
the gums yield glucoses, but no dextrin, when boiled 
with weak acids. 

d. It will be noticed that while physical and chemical 
agencies produce these metamorphoses mostly in one di- 
rection, under the influence of life they go on in either 
direction. 

In the laboratory we can in general only reduce from a 
higher, organized, or more complex constitution to a 
lower and simpler one. In the vegetable, however, all 
these changes, take place with the greatest facility. 

The Chemical Composition of the Carhhydrates. — It 



72 



HOW CROPS GROW. 



has already apj)ea'red that "the substances just described 
stand very closely related to each other in chemical com- 
position. In tlie following table their composition is ex- 
l^ressed in formulae. 



CHEMICAL 


FORMULA OF THE CAEBHYDKATES. 




Amyloses. 




Dried 


CeUulose, 




Cc Hjo Or, 


Soluble cellulose, 




}CcHi,0,* 


Amyloid, 




Starch, 




Cfi Hjn O5 


Soluble starch. 






Aiiiichiliii, 




CeHjoOo* 


AiiiykKlextrin, 






Dextrin, 




Co Hjfi Or, 


luuliu, 


6 (Cc Hio O,) + H2 O = 


C36 H,.,2 31 


Levulin, 


2 (Co Hio O5) + H2 = 


C12 H22 o,i 


Glycogen, 




Co Hjo O5 


recti n. 




(V) 


Arabin, ; 
Metarabin, ; 


2 (Co Hio O5) + H, 


^12 -'I22 ^'11 


Galactin, 




Co Hio O5 


Paragalactin, 




Cfi Hin O5 


Flax-seed mucilage. 




Co Hio Or, 


Quince-seed mucilage, 


Ce H,o O5 + 2 (Ce Hjo 05)-H20 = 


C18 HjR 0]4 


Glucoses. 


Crystallized 




Levulose, 


C, Hi, Oo 


Cg H,, (V, 


Dextrose, 


C,j Hi4 O7 and Cc H,, Oc 


Cfi Hi, ()o 


Galactose, 


Cr. H,2 Ofi 


CfiHijO,, 


Man nose. 


Cr. H^ 0, 


Co 11,2 (V, 


Araliinose, 


Cn H,o 0,. 


C, H,o(), 


Sncroscs. 






Saccharose, 


C12 H,, 0„ 


CnlUO,, 


Maltose, 


c„ H2, 0,2 


Ci2H22()„ 


Lactose, 


C,2 H.,4 0,2 


('12 H22 0,1 


Rafflnose, 


C18 W42 Ool 


C18 H32 Ojr, 



As above formulated, it is seen that all these bodies, 
except arabinose, contain 6 atoms of carbon, or a num- 
ber which is some simple multiple of 6, united to as much 
hydrogen and oxygen as form in most cases 5, 6 or 11 
molecules of water (H.^O). Being thus composed of car- 
bon and the elements of water they are termed Carhliy- 
drates. 

The mutual convertibihty of the carbhydrates is the 



* These soluble bodies when dried probably lose water wliich is 
essential to their comijosition, as on drying they become insoluble. 



THE VOLATILE PART OF PLAKTS. 73 

easier to understand since it takes place by the loss or 
gain of several molecules of water. 

The formulae given are the simj)]est that accord with 
the results of analysis. In case oi many of tlie amyloses 
it is probable that the above formulae should be multi- 
plied by 2, 4, or 6, or even more, in order to reach the 
true molecular weight. 

Isomerism.— Bodies which— like ceUulose and dextrin, or like levn- 
lose and dextrose — are identical in composition, and yet are character- 
ized by difTerent properties and modes of occurrence, are termed iso)n- 
cric ; they are examples of isomerism. These words are of Greek deri- 
vation, and signify of equal tneasiire. 

We must suppose that the particles of isomeric bodies which are com- 
posed of the same kinds of matter, and in the same quantities, exist in 
different states of arrangement. The mason can build, from a given 
nuiriber of bricks and a certain amount of mortar, a simi^le wall, an 
aqueduct, a bridge or a castle. Tiie composition of these unlike struc- 
tures may be the same, both in kind and quantity ; but the structures 
themselves differ immensely, from the fact of the diverse arrangement 
of their materials. In the same manner we may siippose starch to dif- 
fer from dextrin by a difference in the relative positions of the atoms 
of carbon, hydrogen, and oxygen in the molecules which compose 
them. 

By use of " structixral formulae, " it is sought to rei^'esent the different 

arrangement of atoms in the molecules of isomeric bodies. In case 

of siibstanccs so complex as the sugars, attempts of this kind have but 

recently met Avith success. The following formuliT? exhil)it to the 

chemist the probable differences of constitution b-^tween dextrose and 

levulose. 

Dextrose. Levulose. 

H H 

I I 

H— C-O H 



H- 


-C- 

1 


-O H 


H- 


1 
-C- 

1 


-0 H 




L 

1 


-H 


H- 


I 
-c- 

-i- 

1 


-0 H 


() H- 


-0 H 




1 

c- 


-o n 



i-0 



H— C— O H 

I 
H C— O H 

H C— O H 

I 
II ('— O H 

I 
H 

To those familiar with advanced Organic Chemistry the foregoing 
formulce, to some extent, "account for" the chemical characters of 
these sugars, and explain the different products which they yield 
under decomposing influences. 

APPENDIX TO THE CARP.UYDRATES. 

Nearly related to the Carbhydrates are the following substances: — 



74 now CROPS grow. 



Mannite, C,;Hi40r,, is abundant in the so-called manna of the apoth- 
ecary which exudes from the bark of several species of ash that 
grow in the eastern hemisphere {Fraxinus ornus and rotundljolia). It 
likewise exists in the sap of our fruit trees, in edible mushrooms, and 
sometimes is formed in the fermentation of sugar (viscous fermenta- 
tion). It appears in minute colorless crystals and has a sweetisli taste. 
It may be obtained from dextrose and levulose by tlie action of 
nascent hydrogen as liberated from sodium amalgam and water, 

Dalclte, CfiHiiOg, is a crystalline substance foimd in the common cow- 
wheat {Melaitipyrum neinorosum) and in Madagascar manna. It is 
obtained from milk-sugar by the action of sodium amalgam. 

Tlie isomeres mannite and dulcite, when acted on by nitric acid, are 
converted into acids which are also isomeric. Mannite yields saccharic 
acid, which is also formed by treating cane-sugar, dextrose, levulose, 
dextrin and starch with nitric acid. Dulcite yields, by the same treat- 
ment, mucic acid, which is likewise obtained from arabin and other 
gums. Milk-sugar yields both saccharic and mucic acid. Saccharic 
acid is very soluble in water. Mucic acid is quite insoluble. Both 
have the formula CgHjoOg. 

The Pectin-bodies. The juice of niany rij^c fruits, when mixed with 
alcohol, yields a jelly-like jn-ecipitate which has long been known 
under the name of pectin. 'NVhen the firm flesh of acid winter-fruits is 
subjected to heat, as in baking or stewing, it sooner or later softens, 
becomes soluble in water and yields a gummy liquid from which by 
adding alcohol the same or a similar gelatinous substance is separated. 
Fremy supposes that in the puli) " i^ectose " exists which is transformed 
by acids and heat into pectin. 

Exp. 33.— Express, and, if turbid, filter throiigh muslin the juice of a 
ripe apple, pear, or peach. Add to the clear liqiiid its own bulk of 
alcoliol. Pectin is precipitated as a stringy, gelatinous mass, which, 
on drying, shrinks greatly in bulk, and forms, if pure, a white sub- 
stance that may be easily reduced to i^owder, and is readily soluble in 
cold water. 

Pectosic and Peciic Acids. These bodies, according to Fremy, com- 
pose the well-known fruit-jellies. They are both insolid)le or nearly 
so in cold water, and remain suspended in it as a gelatinous mass. 
Pectosic acid is soluble in hot water, and is supposed to exist in those 
fruit-jellies which liquefy on heating but gelatinize on cooling. Pec- 
tic acid is stated to be insoluble in hot water. According to Fremy, 
pectin is changed into pectosic and pectic acids and finally into meta- 
pectic acid by the action of heat and during the ripening process. 

Exp. 35.— Stew a handful of sound cranberries, covered with water, 
just long enough %o make them soft. Observe the speedy solution of 
the firm pidp or " pectose." Strain through muslin. The juice contains 
s(>lul)le iiectin, which may be precipitated from a small portion by 
alcohol. Keep the remaining juice heated to near the boiling point in 
a Avater bath (i. e., by immersing the vessel containing it in a larger 
one of boiling water). After a time, which is variable according to 
the condition of the fruit, and must be ascertained by trial, the juice 
on cooling or standing solidifies to a jelly, that dissolves on warming, 
and reappears again on cooling — Fremy's pectosic acid. By further 



TUE VOLATILE PART OF PLANTS. 



75 



3 



heating, the juice may form a jelly which is permanent when hot— 
pectic acid. 

Other rijje fruits, as quinces, strawberries, peaches, grapes, apples, 
etc., may be employed for this expcu-iment, but in any case the time 
required for the juice to run through these changes cannot be pre- 
dicted safely, and the student may easily fail in attempting to fol- 
low them. 

Scheibler having shown that Fremy's metapectic acid of beets is 
arable acid, it is probable that Fremy's pectin, pectic acid and pectosic 
acid of fruits, are bodies similar to or identical with the gums already 
described. The pectin bodies of fruits have not yet been certainly ob- 
tained in a state of purity, since the analyses of preparations by vari- 
ous chemists do not closely agree. 



The Vegetable Acids. — Nearly every family of the 
vegetable kingdom, so far as investigated, contains one 
or more organic acids peculiar to itself. Those of more 
general occurrence which alone concern us here are few 
in number and must be noticed veiy concisely. 

The vegetable acids rarely occur in plants in the free 
state, but are for the most part united to metals or 
to organic bases in the form of salts. The vegetable 
acids consist of carboxy], OOOH, united generally to 
a hydrocarbon group. They are monobasic, dibasic or 
tribasic, according as they contain one, two or three 
carboxyls. 

The Mo7ioJ)asic Acids, to be mentioned here, fall into 
two groups, viz.: Fatty acids and Oxyfatty acids. 

The Fatty Acids constitute a remarkable "homolo- 
gous series," the names and forniula3 of a number of 
which are here given: 



Formic 

Acetic " 

Propionic *' 

Butyric " 

Valeric " 

Caproic " 
Oenanthylic " 

Caprylic " 

Pelargonic " 

Caprie " 

T^ml)ellic " 

Laurie " 

Tridecylic " 



acid, H, C O O H 
" C H;, C O O H 
«' CgK-.COOH 
" C3H7COOH 
" C4H0COOH 
" C, H„ G O O H 
Co H,. C O O H 
C7 H,., C O O H 
Cs H,7 C O O H 
C, H,,, C O O H 
C,„ H., C O O H 
C„ H20 C O O H 
C12 H25 C O O H 



Found in 
Pine needles, red ants, guano. 
Vinegar and many vegetable juices. 
Yarrow-llowei's. 

Butt er,limburger cheese, parsnip seeds. 
Valerian root, old cheese. 
Butter, cocoanut oil. 
(Artificial.) [fusel oil. 

Butter, cocoanut oil, limbiirger cheese, 
Rose-geranium. 
Butter, cocoanut oil. 
Seeds of California laurel. 
Laurel oil, butter, bayberry tallow. 
(Artificial.) 



7G 



HOW CfiOPS GROW. 



Myristic 


acid,Ci3 H07 C O H 


Nutmeg oil. 


Isocetic 


u 


€14 Hoy C H 


^'eeds of Jatropha. 


Palmitic 


" 


Ci5 Usi C H 


Butter, tallow, lard, palm oil. 


MargHi-ic 


n 


C16 H33 C H 


(Artificial.) 


Stearic 


" 


Ci7 H35 C H 


Tallow, lard. 


Nondecylic " 


C18 H07 C H 


(Unknown.) 


Aracliic 


n 


Ci9 K,,j C H 


Butter, i>eanut oil. 


Medullic 


n 


€,0 H41 C H 


Marrow of ox. 


Beheuic 


n 


C',1 H43 C H 


Oil of Moringa oleifera. 






C,,, H45 C H 
€23 H4, C H 


(Unknown.) 
Beeeli-wood tar. 


Liguoceric 


(( 


Hyeiiic 


t( 


C,4 H49 C H 


Hyena-fat. 






C,5 Hgi C H 


(Unknown.) 




Cerotic 


(( 


€20 H53 C H 


Beeswax, carnauba wax, wool-fat. 



It is to be observed that these ftitty acids make a iieai-ly 
complete series, the first of which contains one carbon 
and two hydrogen atoms, and the last 27 carbon and 54 
hydrogen atoms, and that each of the intermediate aciJs 
differs from its neighbors by CH2. The first tAVO acids 
in this series are thin, intensely sour, odorous liquids 
that mix with water in all proportions ; the third to the 
ninth inclusive are oily liquids whose consistency in- 
creases and whose sourness and solubility in water dimin- 
ish with their greater carbon content. The tenth and 
other acids are at common temperatures nearly tasteless, 
odorless, and fatty solids, which easily melt to oily liquids 
whose acid properties are but feebly manifest. Of these 
acids a few only require further notice. 

Acetic Acid, ail^O^, or CH3COOH, formed in the 
** acetic fermentation" from cider, malt, wine and whis- 
ky, alcohol being in each case its immediate source, 
exists free in vinegar to the extent of about 5 per cent. 
When pure, it is a strongly acid liquid, blistering tiie 
tongue, boiling at 240°, and solidifying at about 60° to a 
white crystalline mass. In plants, acetic acid is said to 
exist in small proj)oi-tion, mostly as acetate of potassium. 

Butyric Acid, C.lisO^, or CH3CH2CH2COOH, in the 
free state, occurs in rancid butter, whose disagreeable 
odor is largely due to its presence. In sweet butter it 
exists only as a glyceride or fat of agreeable qualities. 



THE VOLATILE PAllT OF PLANTS. 77 

The otlier acids of this series ai-e mostly found in veg- 
etable and animal fats or fatty oils. (See p. 85.) 

OxYFATiY Acids. — The acids of this class diiier from 
the corresponding fatty acids by having an additional 
atom of oxygen, or by the substitution of OH for H hi 
the latter. There are two acids of this class that may be 
brietiy noticed, viz.: oxyacetic, orgiycollic acid, and oxy- 
l^ropionic or lactic acid. 

Glycollic Acid, C2H4O3 or HOOH2COOH, exists in 
the juices of plants (grape-vine), and like acetic acid may 
be formed by oxidizing alcohol. 

Lactic, CsHcOs, or CH3OH (OH) COOH, is the acid 
tliat is formed in the souring of milk, where it is produced 
from the milk-sugar by a special organized ferment. It 
is also formed in the 'Mactic fermentation" of cane- 
sugar, starch and gum, and exists accordingly in sour- 
kraut and ensilage. 

The fatty and oxyfatty acids are monohasic, i.e., they 
contain one carboxyl, COOH, and each acid forms one 
salt only, with potassium, for instance, in which the hy- 
drogen of the carboxyl is replace d by the metal. Thus, 
potassium acetate is OH3OOOK. 

The oxyfatty acids are especially prone to form anliy- 
drides by loss of the elements of water. Lactic acid 
cannot be obtained free from admixed water when its 
aqueous solutions are evaporated, without being partially 
converted into an anhydride. Gentle heat up to 270° 
changes it, with loss of water, into so-called lactoladic 
acid,'^ OsHioOg, a solid, scarcely soluble in water, but that 
sloAvly reproduces lactic acid by contact with water, and 
dissolves in alkalies to form ordinary lactates. Lacto- 
lactic acid, heated to 290°, loses water with formation 
of lactide,\ O6H8O4, a solid nearly insoluble in water, but 
also convertible into lactic acid by water, and into lactates 
by alkalies. 

* 2 (C3H6O3) - CoHi.Os + HjO t CoHioOg - C6H8O4 + H^O 



78 uow ciiurs guow. 



Dibasic Acids. — The acids of this 


cL 


iss recjuiring notice 


are 




COOH 


Oxalic aciiL C2H2O4, or 




COOH 






Malonic acid, C3H4O4, or 




pjj /COOH 
CHo-COOH 


Siicciiiic acid, C4Hg04, or 




CH,— COOH 
CH;— COOH 


Malic acid (Oxi/succinic acid), CiHyO^, or 




CH(OH)— COOH 










CH;0H) COOH 


Tartaric acid {Dioxysncciiiic C4HeOo, or 




CH(OH) COOH 


acid), 






The salts formed by union of these acids with metallic 
bases are either primary or secondary, according as the 
metal enters into one or two of the carboxyls. 

Oxalic acid, C2H2O4, exists largely in the common 
sorrel, and is found in greater or less 
quantity in nearly all plants. The pure 
acid presents itself in the form of color- 
less, brilliant, transparent crystals, not 
unlike Epsom salts in appearance (t'ig. Fig. 15. 

15), but having an intensely sour taste. 

Primary potassium oxalate (formerly termed Jicid ox- 
alate of potash), HO OC — COOK, occasions the sour taste 
of the juice of sorrel, from which it may be obtained 
in crystals by evaporating off the water. It may also be 
prepared by dissolving oxalic acid in water, dividing tlie 
solution into two crpial parts, neutralizing''" one of these 
by adding solution of potash and then mixing the two 
solutions and evaporating until crystals form. 

Secondary potassium oxalate (neutral oxalate of potash), 
KOOO — COOK, is the result of fully neutralizing oxalic 
acid with potash solution. It has no sour taste. 

Primary calcium oxalate exists dissolved in the colls 
of plants so long as they are in active growth. Second- 
ary calcium oxalate is extremely insoluble in water, and 

* As described in Exp. 38. 



THE VOLATILE PART OF PLAINTS. 79 

very frequently occurs within the plant as microscopic 
crystals. These are found in large quantity in the ma- 
ture leaves and roots of the beet, in the root of garden 
rhubarb, and especially in many lichens. 

Secondary ammonium oxalate is employed as a test for 
calcium. 

Exp. 36.— Dissolve 5 grams of oxaUc acid in 50 e. e. of hot water, add 
solution of ammonia or solid carbonate of ammonium until the odor of 
the latter slightly prevails, and allow the liquid to cool slowly. Long, 
needle-like crystals of ammonium oxalate separate on cooling, the 
compound heing sparingly soluble in cold water. Preserve for future 

use. 

Exp. 37.— Add to any solution of lime, as lime-water (see note, p. 20), 
or hard well-water, a lew drops of solution of ammonium oxalate. 
Secondary Calcium oxalate immediately appears as a white, powdery 
precipitate, which, from its extreme insolubility, serves to indicate the 
presence of the minutest quantities of lime. Add a few drops of hydro- 
chloric or nitric acid to the calcium oxalate; it disapi)ears. Hence 
ammonium oxalate is a test for lime only in solutions containing no free 
mineral acid. (Acetic and oxalic acids, however, have little effect vipon 
the test.) 

Malonic acid and Succinic acid occur in plants in 
but small quantities. The former has been found in 
sugar-beets, the latter in lettuce and unripe grapes. 

Malic acid, O4H6O5, is the chief sour principle of ap- 
ples, currants, gooseberries, plums, cherries, strawberries, 
and most common fruits. It exists in small quantity in a 
multitude of plants. It is found abundantly in the gar- 
don rhubarb, and primary potassium malate may be ob- 
tained in crystals by simply evaporating the juice of the 
leaf-stalks of this plant. It is likewise abundant as cal- 
cium salt in the nearly ripe berries of the mountain asli, 
and in barberries. Calcium malate also occurs in con- 
siderable quantity in the leaves of tobacco, and is often 
encountered in the manufacture of maple sugar, separat- 
ing as a white or gray sandy powder during the evapora- 
tion of the sap. 

Pure malic acid is only seen in the chemical laboratory, 
and presents white, crystalline masses of an intensely 
sour taste. It is extremely soluble in water. 




80 now CROPS r,ROw. 

Tartaric acid, C4H0O,;, is abundant in the grape, 
from the jaice of whioh^ during fermentation, it is de- 
posited as argol. Tliis, on purification, 
yields the cream of tartar (bitartrate of 
])otasli) of commerce. Tartrates of po- 
tassium and calcium exist in small quan- 
tities in tamarinds, in the unripe berries ^'^c- ^^' 
of the mountain ash, in the berries of the sumach, iu cu- 
cumbers, potatoes, pineapples, and many other fruits. 
The acid itself may be obtained in large glassy crystals 
(see Fig. 16), which are very sour to the taste. 

Of the Tribasic Acich known t ) occur in phmts, but 
one need be noticed here, viz., cilric acid. 

c ir, c o o li 

I ' 

Cc Hg O7, or (' (O H) C O O H 
C Ho C O O H 

Citric acid exists in the free state in the juice of the 
lemon, and in unripe tomatoes. It accompanies malic 
acid in the currant, gooseberry, cherry, strawberry, and 
raspberry. It is found in small quantity in tobacco 
leaves, in the tubers of the artichoke {Hclianthus), in the 
bulbs of onions, in beet-roots, in coffee-berries, in seeds of 
lupin, vetch, the pea and bean, and in the needles of the 
fir tree, mostly as potassium or calcium salt. It also 
exists in cows' milk. 

In the pure state, citric acid forms large transparent or 
white crystals, very sour to the taste. 

I?elattons of the Vef/etable Acids to each other, and to the Amylases.-^ 
OxaUc, malic, tartaric and citric acids usuaUy occur together in onr 
ordinary fruits, and some of them undergo mutual conversion in the 
living plant. 

According to Lielng, the unripe berries of the mountain ash contain 
much tartaric acid, which, as the fruit ripens, is converted into malic 
acid. Tartaric acid can be artifieially transformed into malic acid, and 
this into succinic acid. 

Wlien citric, malic and tartaric acids are boiled wU.h nitric acid, or 
heated with caustic potasli, tliey all yield oxalic acid. 

Cellulose, starch, dextrin, the sugars, yield oxalic acid when heated 



THE VOLATILE PART OF PLANTS. 81 

with iiotash or nitric acid. Commercial oxalic acid is tluis made from 
sawdust. 

Gum (Aral)ic), sugar and starcli yield tartaric acid by tlie action of 
nitric acid. 

Definition of Acids, Bases, and Salts. — In tbe popular 
sense, an acid is any body having a sonr taste. It is, in 
fact, true that all sour substances are acids, but all acids 
are not sour, some being tasteless, others bitter, and soiue 
sv^eet. A better characteristic of an acid is its capability 
of foi'ming scdts by its interaction with l)ases. The strong- 
est acids, i. e., those bodies Avhose acid characters are most 
liighly developed, if soluble, so as to have any effect on 
the neryes of taste, are sonr, viz., sulphuric acid, phos- 
phoric acid, nitric acid, etc. 

Bases are the opposite of acids. The strongest bases, 
when soluble, are bitter and biting to the taste, and cor- 
rode the skin. Potash, soda, lime, and ammonia are ex- 
amples. Magnesia, oxide of iron, and many ether com- 
pounds of metals witli oxygen, are insoluble bases, and 
hence destitute of taste. Potash, soda, and ammonia 
are termed alkalies; lime and magnesia, cdhali-carths. 

Salts are compounds that result from the luutual ac- 
tion of acids and bases. Thus, in Exp. 20, the salt, cal- 
cium phosphate, was produced by bringing together 
phosphoric acid, and the base, lime. In Exp. 37, cal- 
cium oxalate was made in a similar mannei*. Common 
salt — in chemical language, sodium chloride — is formed 
when caustic soda is mixed with hydrochloric acid, water 
being, in this case, produced at the same time. 

NaOH 4- HCl = NaCI + H2O 

Sodium hydroxide. Hydrochloric acid . Sodium chloride. Wetter. 

' In general, salts having a metallic base are formed by 
substituting the metal for the hydrogen of the acid ; or if 
an organic acid, for the hydrogen that is united to oxy- 
gen, i.e., of carboxyl, COOH. 

Ammonia, NHg, and many oi'ganic bases unite directly 
to acids in forming salts. 
6 



NH3 


+ 


HCl 


Ammonia. 




Hydrochloric acid. 


NH3 


+ 


CH3COOH 


Ammo/da, 




Acetic acid. 



HOW CROPS GROW. 

NH4CI 

AmtnoniuDi chloride.* 

CHsCOONH^ 
Ammonium Acetate. 

Test for acids and alkalies. — Many vegetable colors are altered by sol- 
uble acids or soluble bases (alkalies), in such a manner as to answer the 
puri:)ose of distinguishing these two classes of bodies. A solvition of 
cochineal may be employed. It has a ruby-red color when concen- 
trated, but, on mixing with much pure water, becomes orange or yel- 
lowish-orange. Acids do not affect this color, while alkalies turn it to 
an intense carmine or violet-carmine, which is restored to orange by 
acids. 

Exp. 38. — Prepare tincture t of cochineal by pulverizing 3 grams of 
cochineal, and shaking frequently with a mixture of 50 c. c. of strong 
alcohol and 200 c. c. of water. After a day or two, pour olf the clear** 
liquid for use. 

To a cup of water add a few drops of strong sulphuric acid, and to an- 
other similar quantity add as many droits of ammonia. To these liquids 
add separately 5 drops of cochineal tincture, observing the coloration 
in each case. Divide the dilute ammonia into two portions, and pour 
into one of them the dilute acid, until the carmine color just passes into 
orange. Sliould excess of acid liave been incautiously used, add am- 
monia, until tlie carmine reappears, and destroy it again by new por- 
tions of acid, added dropwise. Tlie acid and base tlius nciitralize each 
other, and the solution contains sulpliate of ammonia, but no free acid 
or base. It will be found tliat the orange-cochineal indicates very mi- 
nute quantities of ammonia, and the carmine-cochineal correspond- 
ingly small quantities of acid. 

In the formation of salts, the acids and bases more or 
less neutralize each othei'^s propertieSy and their com- 
pounds, when soluble, have a less sour or less acrid taste, 
and act less vigorously on vegetable colors than the acids 
or bases themselves. Some soluble salts have no taste 
at all resembling either their base or acid, and have 
no eifect on vegetable colors. This is true of common 
salt, glauber salts or sulphate of sodium, and saltpeter or 
nitrate of potassium. Others exhibit the properties of their 
base, though in a reduced degree. Carbonate of am- 
monium, for example, has much of the odor, taste, aiitf 



* Also termed ammonie chloride, ammonia hydrochlorate, ammonia 
hydrochloride, and formerly nniriate of ammoiiia. 

t Tinctures, in the language of the apothecary, are alcoholic solutions. 
Tincture of litmus (procurable of the ai^otliecary), or of dried red cab- 
bage, may also be employed. Litmus is made red by soluble acids, and 
blue by soluble bases. With red cabbage, acids develop a purple, and 
the bases a green color. 



THE VOLATILE PART OF PLANTS. 



effect on vegetable colors that belong to ammonia. Car- 
bonate of sodium has the taste and otlier properties of caus- 
tic soda in a greatly mitigated form. On the other hand, 
sulpliates of aluminum, iron, and copper, have slightly 
acid characters, 
y, S. Fats an^d Oils (Wax). — Vfe have only space here 
to notice this important class of bodies in a very general 
manner. In all plants and nearly all parts of plants wo 
find some representatives of this grouj^ ; but it is chiefly 
in certain seeds that they occur most abundantly. Thus 
the seeds of hemp, flax, colza, cotton, bayberry, peanut, 
butternut, beech, hickory, almond, sunflower, etc., con- 
tain 10 to 70 per cent of oil, which may be in great part 
removed by pressure. In some plants, as the common 
bayberry and the tallow-tree of Nicaragua, the fat is 
solid at ordinary temperatures, and must be extracted by 
aid of heat ; while, in most cases, the fatty matter is 
liquid. The cereal grains, especially oats and maize, con- 
tain oil in appreciable quantity. The mode of occur- 
rence of oil in plants is shown in Fig. 17, which repre- 
sents a highly magnified section of the flax-seed. The 
oil exists as minute, transparent globules in the cells, /. 
From these seeds the oil may be completely extracted by 

ether, benzine, or sulphide of car- 
bon, which dissolve all fats with 
readiness, but scarcely affect the 
other vegetable principles. 

Many plants yield small quanti- 
ties of wax, which often gives a 

^ ^_ -_,,,^^__^C^C g^<^ssy coat to their leaves, or 

^ j'^t^ ■■ "' C^^ forms a bloom upon their fruit. 

The lower leaves of the oat-plant 
at the time of blossom contain, in 
the dry state, 10 per cent of fat 
and wax (Arendt). Scarcely two 
of these oils, fats, or kinds of wax, are exactly alike in 




OOOOC3 



•lif^^^ 



Fis:. 17. 



84 now CROPS grow. 

their j^roperties. They differ more or less in taste, odor, 
and consistency, as well as in their chemical composition. 
The '^oils" are the simplest in chemical composition, 
and have the lowest melting point:;. Tlie '"fats" li;ivc 
larger content of carbon, ani higher point;i of fusion. 
Tiie varieties of wax are most complex in composition, 
and have the highest melting points and greatest content 
of carbon. These differences are mostly gradatioiial. In 
chemical constitution these bodies are alike. 

Exp. 39.— Place a liaiidful of fine and fvesli corn or oatmeal, wliich lias 
been dried for an hour or so at a heat not exceeding 212 \ in a but He. 
Pour on twice its bulk of ethei-, cork tightly, and agitate freq\iently for 
half an hour. Drain otf the liquid (filter, if need be) into a clean porce- 
lain dish, and allow the ether to evaporate. A yellowish oil remains, 
which, by gently wanning for some lime, loses the smell of ether and 
becomes quite i)ure. 

The fatty oils mnst not be confounded with the ethe- 
real, essential, or volatile oils, which, liowever, do not occur 
to much extent in agricultural plants. The foi-mer can 
not evaporate except at a liigli temperature, and when 
brought upon paper leave a permanent ^'grease spot." 
The latter readily volatilize, leaving no trace of their 
presence. The former, when pure, are witliout smell or 
taste. The latter usually possess marked odors, which 
adapt many of them to use as perfumes. 

In the animal body, fat (in some insects, wax) is formed 
or appropriated from the food, and accumulates in con- 
siderable quantities. How to feed an animal so as to 
cause the most rapid and economical fatteni7ig is one of 
the most important questions of agricultural chemistr}^ 

However greatly the various fats may differ in external 
characters, they are all mixtures of a few elementary fats. 
The most abundant and commonly-occurring fats, espe- 
cially those which are ingredients of the food of man and 
domestic animals — e.g., tallow, olive oil, and butter — con- 
sist mainly of three substances, which we may briefly 
notice. These elementary fats are Stearin, Palmiiin, 



THE VOLATILE PART OF PLANTS. 85 

and Olein,* and tliey consist of carbon, oxygen, and hy- 
drogen, the first-named element being greatly pre|);)n- 
derant. 

Stearin is represented by the formula O57H110O,;. It 
is the most abundant ingredient of the common fats, a^id 
exists in largest proportion in the harder kinds of tallo.v. 

Exp. 40.— Heat mutton or beef taUow in a bottle that may be liylilly 
corked, with ten times its buUc of coneentrated ether, until a elear 
solution is obtained. Let cool slowly, when stearin will crystallize out 
in j)early scales. 

Palmitin, C51H93O6, receives its name from the palm 
oil, of Africa, in which it is a large ingredient. It forms 
a good part of butter, and is one of the cliief constituents 
of beeswax, and of bayberry tallow. 

Olein, C57II104OC, is the liquid ingredient of fals, 
and occurs most abundantly i!i the oils. It is j)roparod 
from olive oil by cooling down to the freezing point, 
Avhcn tlic stearin and the palmitin solidify, leaving the 
o^eiu still in the liquid state. 

other elementary fats, viz., biityrin, laurin, myristin, etc., occur in 
small quantity in butter, and in varioxis vegetable oils. Flaxseed oil 
contains linolein ; castor oil, ricinolein, etc. 

We have already given the formulae of the principal 
fats, but for our purposes, a better idea of their composi- 
tion may be gathered from a centesimal statement, viz. : 

CENTESIMAL COMPOSITION OF THE ELEMENTARY FATS. 

Stearin. Palmitin. Olcin. 

Carbon 7G.6 75.9 77.4 

Hydrogen 12.4 12.2 11.8 

Oxygen 10.0 11.9 10.8 

100.0 100.0 100.0 

Saponification. — The fats are characterized by forming 
soaps when lieated with strong potash or soda-lye. They 
are by this means decomposed, and give rise to faitif 

* Marriarin, formerly thought to be a chemically-distinct fat, is a mix- 
ture of stearin and ]ialmitin. Olromnv yariny is the commercial designa- 
tion of an artiticially-oblained mixture of fats, animal or vegetable, 
that has nearly the consistence of dairy butter. 



8G now CROPS GROW. 

acids, which remain combined with the alkali-metal, 
and to glycerin, a substance which acts as a base. The 
fats are therefore termed glycerides. 

Exp. 41. — Heat a bit of tallow with strong solution of caustic potash 
until it completely disappears, and a soap, soluble in water, is obtained. 
To one-half the hot solution of soap, add hydrochloric acid until the lat- 
ter predominates. An oil will separate wliich gathers at the top of the 
liquid, and, on cooling, solidifies to a cake. This is not, however, the 
original fat. It has a different melting point, and a different chem- 
ical composition. It is composed of the tliree fatty acids, corres- 
ponding to the elementary fats from which it was produced. 

Wlien saponified by the action of potash, stearin yields 
stearic acid, CigHseOa ; palmitin yields iMlmitic acid^ 
C1GH32O2 ; and olein gives oleic acid, C18H34O2.* The 
so-called stearin candles are a mixture of stearic and 
palmitic acids. The glycerin, CsIIsOs, that is simul- 
taneously produced, remains dissolved in the liquid. 
Glycerin is found in commerce in a nearly pure state, as 
a colorless, syrupy liquid, having a pleasant, sweet taste. 

The chemical act of saponification consists in tlie re-ai-rangement of 
the elements of one molecule of fat and three molecules of water into 
three molecules of fatty acid, and one molecide of glycerin. 

Palmitin. Water. Palmitic acid. Glycerin. 

CsiHogOe + 3(H20) = 3 (CioH^^O,) + CsHgOg 

Saponification is likewise effected by the influence of strong acids 
and by heating with water alone to a temperature of near 400^ F. 

Ordinary soap is nothing more than a mixture of stearate, i)almitate, 
and oleate of potasssium or of sodium, witli or without glycerin. Com- 
mon soft soap consists of the potassium comi^ounds of tlie above- 
named acids, mixed Avith glycerin and water. Hard soap is usually the 
corresponding sodium-compound, free from glycerin. When soft soaj) 
is boiled with common salt (chloride of sodium), hard soap and chlo- 
ride of potassium are formed by transposition of the ingredients. On 
cooling, hard-soap forms a solid cake upon the liquid, and the glycerin 
remains dissolved in the latter. 

Relations of Fats to Carhliydrates. — The oil or fat of 
plants is in many cases a product of the transformation 
of starch or other member of the celhilose group, for the 
oily seeds, when immature, contain starch, which van- 

* Oleic acid differs from stearic acid in containing two atoms loss of 
hydrogen, and is one of a series that l)ear this relation to the fatty acids 
of corresi:)onding content of carbon. 



THE VOLATILE PAKT OF PLANTS. 87 

ishes as tliey ripen, and in the sugar-cane the quantity 
of wax is said to be largest when the sugar is least abund- 
ant, and vice versa. In germination the oil of the seed 
is converted back again into starch, sugar, etc. 

The Estimation of Fat (including wax) is made by warming the pul- 
verized and dry substance repeatedly with renewed quantities of ether, 
or sulpliide of carbon, as long as the solvent takes up anything. On 
evaporating the solutions, the fat remains, and after drying thorough- 
ly, may be weighed. The e^lier extract thus obtained is usually accom- 
panied by a small amount of other substances, especially chlorophyll 
and lecithin, and is hence properly termed crude fat. 

PROPOKTIO^^'S OF CKUDE FAT IN VAKIOUS VEGETABLE PRODUCTS. 

Per cent. Per cent. 

Meadow grass 0.8 Turnip 0.1 

Red clover (green) 0.7 AVheat kernel 1.6 

Cabbage 0.4 Oat " 1.6 

Meadow hay 3.0 Maize " 7.0 

Clover hay 3.2 Fea " 3.0 

Wheat straw 1.5 Cotton seed 34.0 

Oatstraw 2.0 Flax " 34.0 

Wheat bran 1.5 Colza " 45.0 

Potato tuber 0.3 

r- 

O %^ The Albuminoids ou Proteids. — The bodies of 

this class essentially differ from those of the groups hith- 
erto noticed, in the fact of their containing, in addition 
to carbon, oxygen, and hydrogen, 15 to 18 per cent of 
nitrogeyi, with a small quantity of sulplixir, and, in some 
cases, perhaps i:)liospliorus. 

These bodies, though found in some proportion in all 
parts of plants, being everywhere necessary to growth, 
are chielly accumulated in the seeds, especially in those 
of the cereal and leguminous grains. 

The albuminoids, or pi'oteids^ that occur in plants are 
so similar, in many characters, to those which constitute 
a large portion of every animal organism, that we may 
advantageously consider them in connection with the 
latter. 



* The nomenclature of these substances is unavoidably confused. 
They are often termed nitiogenous or nitrogeni/ed bodies, also albu- 
minous bodies, and jn'oTrin bodies. The term all)nminoids has b.cen 
latterly restricted, by some autliors, to the sul)stances of which gela- 
tine is a type. The' word albuminates is applied to syntouin and 
casein. 



88 HOW CROPS GROW. 

Three familiar representatives of this class of bo^^lies 
are, albumin, or the white of egg ; ji'yrin, or the clot of 
blood, and casein, which yields the cuivl of njilk. 

General (Jharacters. — Many of these substances occur 
in two very distinct modifications, one form bjing sohibb 
in water, or in highly-diluted acids or alkalies, or in salt- 
solutions, the other insoluble in these liquids. 

Some of the soluUe jjrotcids we find naturally dissolved 
in the juioes of living plants and animals. Some may bo 
obtained in the solid form by evaporating oil at a very 
gentle heat the water which is naturally associated with 
them. They then appear as nearly colorless or yellovv^- 
isli, amorphous solids, destitute of odor or taste, which 
dissolve again in water, but are insoluble in alcohol. 

Soluble compounds of proteids with magnesium or 
iron occur in plants, or may be obtained from the blood 
of animals, in the form of white or red crystals. 

Solutions of most of the albuminoids are readily coagu- 
lated by heat and by concentrated mineral acids, the 
albuminoids being thereby themselves chemically changed 
and made insoluble. Some coagulate spontaneously. 

The insoluble albuminoids, some of which also occur 
naturally in plants iind animals, are, when purified as 
much as possible, white, flocky, lumpy or fibrous bodies, 
quite odorless and tasteless. 

The albuminoids, when subjected to hcjit, melt and 
burn with a smoky llame and a peculiar odor — that of 
burnt h:iir or horn — while a shinimr charcoal remains 
which is difficult to consume. 

Tests for the Albuminoids.— TIxq chemist employs the behavior of 
the albuminoids towards a number of reagents* as tests for their pres- 
ence. Some of these are so delicate and characteristic as to allow the 



* Reagents are substances commonly employed for the rccognit ion 
of bodies, or, generally, to produce chemicarchanges. All chemical 
plienomena result from the mutual action of at least tAvo eloniont'^, 
which thus act and react on each other. Hence the snbstanco tliat 
excites chemical changes is termed a reagent, and the phenomena or 
results of its application are called reactions. 



THE VOLATILE PART OF PLA:t^TS. 89 

distinction of this class of snbstaiices from all others, even in micro- 
scoi)ic observations. 
1. "Solution of iodine colors tlieni intensely yellow or bronze. 

2. Warm and strong hydrochloric acid colors these bodies blue, 
violet, or brown, or, if applied in large excess, dissolves them to a 
liquid of these colors. 

3. In contact with nitric acid, especially when hot, they are stained a 
deep 'and vivid yellow. Silk and wool, which consist largely of pro- 
teids, are commonly dyed or j^rinted yellow by means of nitric acid. 

4. A solution of mercuric nitrate in excess of nitric acid,* tinges them 
of a deep red color. This test enables us to detect albumin, for exam- 
ple, even where it is dissolved in 20,000 parts of water. 

5. With caustic soda and very dilute solution of copper svlphate, 
successively applied, the proteids give a violet color which is intensi- 
fied by warming. (Biuret test.) 

The Albumins are soluble in water; the solutions as 
naturally occurring, unless very dilute, are coagulated by 
heat. 

Bgg Albiimi7i. — The white of a hen's egg on drying 
yields about 12 per cent of albumin in a state of tol- 
erable purity. The fresh white of eggs serves to ilhis- 
trate the peculiarities of this substance, and to exhibit 
the deportment of the albuminoids generally toward the 
above-nameil reagents. 

Exp. 42. — Beat or whip the white of an egg so as to destroy the deli- 
cate transparent membrane in the cells of Avhich the albumin is held, 
and agitate a portion of it with water ; observe that it mostly dissolccs 
in the latter. The solution is turbid from i^resence of globulin. 

Exp. 43. — Heat a part of the undilutetl white of egg in a tube or cui). 
At 1G5'^F. it becomes oparpie, white, and solid (coagulates), and is eon- 
verted into the insoluble modification. A higher heat is heedful to 
coagulate solutions of albumin, in i^roportion as they are diluted with 
water. 

Exp. 44. — Add strong alcohol to a portion of the solution of albumin 
of Exp. 42. It precipitates the albumin, whicli for a time remains solu- 
ble in water, but later coagulates and becomes insolabh>. 

Exp. 45. — Observe that allnimin is coagulated by strong acids applied 
in small quantity, especially by nitric acid. 

Exp. 46.— Put a little albumin, either soluble or coagulated, into each 
of five test tubes. To one, add solution of iodine; to a second, strong 
hydrochloric acid; to a third, nitric acid; to a fourth, nitrate of mer- 
cury, and to the last a few drops of solution of copper sulphate, and 
then a little caustic soda or potash solution. Observe the characteristic 
colorations that appear immediately, or after a time, as described 
above. In the last four cases the reaction is hastened by a gentle heat. 



* This solution, known as Millon's reagent, is prepared by dissolving 
mercury in its own weight of nitric acid of sp. gr. 1.4, h(>ating toward 
the close of the process, and finally adding to the liquid twice its bulk 
of water. 



90 now CROPS GliOW. 

Serum Albumin occurs dissolved in the blood, in milk, 
and in nearly nil the liquids of the healthy animal body ex- 
cept the urine. Its characters are slightly diiferent from 
those of egg-albumin. The albumin of the blood may 
be separated by heating blood-serum (the clear yellow 
liquid that floats above the clot). The albumin of milk 
coagulates when milk-serum (whey) is heated to near 
boiling. 

On boiling entire milk, albumin coagulates, and, mixed 
with fat and casein, is deposited as a tough coating on 
the sides of the vessel. 

Animal albumin remains, when its solutions are evap- 
orated at a temperature below 140"" F., as a yellowish trans- 
lucent and friable solid, which easily dissolves in water. 

Vegetable Albumin. — In the juices of all plants is 
found in small quantity a substance which agrees in 
many respects with animal albumin, and has been termed 
vegetable albumin. The cle-.ir iuice of the potato tuber 
(which may be procured by grating potatoes, squeezing 
the pulp in a cloth, and letting the liquor thus obtained 
stand in a cool place until the starch has deposited) con- 
tains such a body in solution, as may be shown by heat- 
ing to near the boiling point, when a coagulum separates, 
which, after boiling successively with alcohol and ether 
to remove fat and coloring matters, in its chemical reac- 
tions and composition closely approaches the coaguhitcd 
albumin of eggs. 

The juice of succulent vegetables, as cabbage, yields 
a similar substance in larger quantity, though less pure, 
by the same treatment. 

Water which Inis been agitated for some time in con- 
tact with flour of wheat, rye, oats, or barley, is found 
by the same method to have extracted an albuminoid from 
these grains. 

The coacc^ilum, llius pi-opavod from any of these sourees, cxliibits the 
reactions characteristic of tlie albuminoids, when put in contact with 
nitrate of mercury, nitric or liydroohloric acid. 



THE VOLATILE PART OF PLANTS. 91 

Exp. 47.— Prepare Impure vegetable albumin from potatoes, cabbage, 
or Hour, as above described, and ai^jjly the nitrate of mercury test. 

As already intimated, albumin is chemically changed 
or decom23osed in the process of coagulation. Coagu- 
lated albumin is not readily dissolved by dilute acids or 
by dilute aqueous solutions of alkali. 

The so-called vegetable albumin is mostly known only 
after coagulation by heat, and has been but imperfectly 
studied. According to Eitthausen, the coagulum ob- 
tained by heating the juice of potato tubers or the aque- 
ous extracts of peas aud horse-beans ( Vicia faba) is solu- 
ble in dilute potash aud in acetic acid; it is therefore 
not albumin. Sidney Martin reports a genuine albumin 
in the juice of the papaw, but its composition has not 
been determined. 

Fibrin. — Animal Fibrin is insoluble in water, alco- 
hol and salt-solutions ; it swells up in dilute acids, dis- 
solves in alkalies, and is coagulated by heat. 

The blood of the higher animals, when in the body or 
when fresh drawn, is perfectly fluid. Shortly after it is 
taken from the veins it partially solidifii's — it coagulates 
or becomes clotted. It hereby separates into two por- 
tions, a clear, pale-yellow liquid— the serum — and the 
clot. As already stated, the serum contains albumin. 
On persistently squeezing and washing the clot with 
water, the coloring matter of the blood is removed, and 
a white stringy mass remains, which consists chiefly of 
filjrin, being a decomposition-product of another albu- 
minoid, fibrinogen. 

In very dilute hydrochloric acid, flbrin swells up, but 
does not dissolve. When freshly prepared, it absorbs 
oxygen from the air and gives off carbon dioxide. Heat- 
ing to 176° to 212° coagulates and shrinks it, and ren- 
ders it less elastic and incapable of absorbing oxygen. 

Exp. 48.— Observe the separation of blood into serum and clot ; coag- 
ulate the albumin of the former by heat, aud test it with warm hydro- 
chloric acid. Tic up the clot in a piece of muslin, and squeeze and 



92 HOW CROPS GROW. 

wasli in water until coloring matter ceases to run off. Warm it with 
nitric acid as a test. 

Flesh- Filr in. — If a piece of lean beef or other dead 
animal muscle be repeatedly squeezed and washed in 
water, the coloring matters are gradually removed and a 
white residue is obtained which resembles blood-fibrin in 
its external characters, and as it represents the fibers of 
the original muscle, and was supposed to be a simple 
albuminoid, it was formerly designated flesh-fibrin. It 
is, however, a mixture consisting largely of 7nyosin (see 
p. 97). It mostly dissolves in very dilate hydrochloric 
acid to a clear liquid, from which addition of much com- 
mon salt, or of a little alkali, throws down syiitonin. 
The term flesh-fibrin is therefore no longer properly em- 
ployed to designate a distinct chemical substance. 

Vegetable fibrin. — When wheat-flour or rye-flour is 
mixed with a little water to a thick dough, and this is 
washed and kneaded for some time in water, the starch 
and albumin are mostly removed, and a yellowish tena- 
cious mass remains, which bears the name glut C7i. When 
wheat is slowly chewed, the saliva carries off the starch 
and other matters, and the gluten mixed with bran is 
left behind — well-known to country lads as " wheat- 
gum." 

Exp. 49.— Wet a handful of good, fresh, wheat-flour slowly with a lit- 
tle water to a sticky dough, and squeeze this under a fine streani of 
water until the latter runs off clear. Heat a portion of this gluten with 
Millon's reagent. 

Gluten is a mixture of several albuminoids, and con- 
tains also some starch and fat. When boiled with alco- 
hol it is partially dissolved.* The portion insoluble in 



* The dissolved portion Ritthausen found to consist of two distinct 
albinninoid or rather glutinoid bodies, viz. : 

GlimJin, or vegetable glue, is very soluble in water and alcohol. It 
strongly resemV^les animal glue and chiefly gives to wheat dough its 
tenacious qualities. 

Mucedin resembles glladin, but is less sohdile in strong alcohol, and 
is insoluble in water. When moist, it is yellowiah-wliite in color, has 
a silky luster, and slimy consistence. It exists also in gluten made 
from rye grain. (Ritthausen, Jo«r./ii/- rrakt. Chem.,S8,l-ii, arirf 99,463.) 



THE VOLATILE PART OF PLANTS. 93 

strong alcohol Liebig first designated as vegetalle fibrin. 
Eitthausen found this to be a mixture of two bodies, 
which he distinguished as gluten-casein and gluten-fibrin. 
The latter is extracted from ghiten by hot weak alcohol 
and separates on partially removing the alcohol by evap- 
oration. 

The albuminoids of crude gluten dissolve in very dilute potash-solu- 
tion (J to 1 parts potash to 1,000 parts of water), and the liquid, after 
standing some days at rest, may be poured otF from any residue of 
starch. On adding acetic acid in slight excess, the inirified albuminoids 
are separated in the solid state. By extracting successively with weak, 
with strong, and with absolute alcohol, the gluten-casein of Ritthausen 
remains undissolved. 

On evaporating the alcoholic solution to one-half, there separates, on 
cooling, a brownish-yellow mass. This, when treated with absolute 
alcohol, leaves gluten-fibrin nearly pure. 

Vegetable fibrin is readily sokible in hot dilute alcohol, 
but slightly so in cold dilute, and not at all in abcolute al- 
cohol. On prolonged heating with alcohol, it becomes in- 
soluble in that liquid. It does not dissolve in Avater. It 
has no fibrous structure like animal fibrin, but forms, 
when dry, a tough, horn-like mass. In composition it 
approaches washed muscle, but differs considerably from 
blood-fibrin. 

Wheat contains or yields* but a small proportion of 
fibrin and less appears to exist in hard than in the soft 
wheats. Eye contains less than wheat. Barley, from 
which no gluten can be got, yields to alcohol a small pro- 
portion of fibrin. 

Maize-fibrin, Zein. — The meal of Indian corn, unlike 
that of wheat and rye, when made into a dough, forms 
no gluten, but it yields to warm, weak alcohol some 
7 per cent of fibrin quite similar to that from wheat, 
though of somewhat different comi^osition. 



* Weyl and Bischof believe that gluten does not pre-exist in wheat 
and rye, just as fibrin does not exist in living blood, but is a result of 
chemical change during the wetting and kneading of the flour to a 
dough. According to them a strong solution of common salt extracts 
from wheat flour vegetable globulin (see p. fi7), and the residue, when 
kneaded with water, forms no gluten. If, however, the salt solution of 
globulin, in contact with the Dour, is largely diluted with water, the 
flour will yield gluten by kneadmg. 



94 HOW CROPS GROW. 

Casein. — Animal Casein is the peculiar albuminoid of 
milk, in which it exists dissolved to the amount usually 
of 3 to 6 per cent. By saturating milk with magnesium 
sulphate the casein separates as an opaque white precipi- 
tate. Thus obtained it is freely soluble in water. Casein 
is also precipitated from milk by adding a little acetic or 
other acid, but is then nearly insoluble in water, has 
a decided acid reaction, and reddens blue litmus. The 
spontaneous curdling of milk, after standing at or- 
dinary temperatures for some time, appears to be directly 
due to the lactic acid which develops from milk-sugar as 
the milk sours. When milk is swallowed by a mamma- 
lian animal it curdles directly, and in the making of cheese 
the casein of milk is coagulated by the use of rennet, which 
is an infusion of tlie membrane lining the calf's stomach. 
Coagulated casein, though insoluble in water, dissolves 
in very dilute acids, and also in very dilute alkalies. 

The coherent cheese curd wdiich is separated from milk 
by rennet is doubtless a decomposition-product of casein, 
and carries v/ith it a considerable portion of the phosphates 
and other salts of the milk. These salts are not found in 
the casein precipitated by acids, being kept in solution 
by the latter, but casein ai)pears to contain a small amount 
of phosphorus (erpiivalent to 0.9 per cent phosphoric 
oxide) in organic combination. Skim-milk clieese, when 
new, consists mainly of coagulated casein with a little 
fat. Cheese made from entire milk contains most of the 
fat of the milk. 

Exp. 50. — Observe the coagulation of casein when niillv is treated 
witli a few drops of dilute hydrochloric acid. Test the curd with 
nitrate of mercury. 

Exr. 51. — Boil milk with a little magnesium sulphate (Epsom salts) 
until it curdles. 

Vegetable Casein. — Several distinct subctances have 
been described as vegetable caseins. Our knowledge with 
regard to them is in many impoi'tant respects very defi- 
cient. Even their elementary composition is a matter of 
uncertainty. 



THE VOLATILE PART OF PLAINTS. 95 

Gluten- Casein. — That part of the gluten of wheat 
which is insoluble in cold alcohol is digested in a highly 
dilute solution of potash, and the clear liquid is made 
faintly acid by acetic acid. The curdy white precipitate 
thus obtained, after washing with water, alcoliol and 
ether, and dried, is the gluten-casein of Eitthausen. It 
is insoluble in water, and in solutions of common salt, 
easily soluble in weak alkalies and coagulated by acids. 
Eitthausen obtained this body from wheat, rye, barley, 
and buckwlieat. 

Legumin is the name that has been applied to the chief 
albuminoid of oats, peas, beans, lupins, vetches, and otlier 
legumes. It is exti'acted from the pulverized seeds by 
dihite alkalies, and is thrown down from these solutions 
by acids. From some leguminous seeds it may be partially 
extracted by pure water, probably because of the presence 
of alkali-phosphates which serve to dissolve it. It is 
generally mixed with conglutin, from which it may be 
separated by soaking in weak brine (a 5 per cent solution 
of common salt). Thus obtained, it is insoluble in pure 
water and in brine, but soluble in dilute alkalies, and has 
a decided acid reaction. Legumin, as existing in the 
horse-bean ( Vicia faha), is soluble in brine, but after solu- 
tion in alkali and precipitation with acids, is insoluble 
in salt solution. The casein, animal or vegetable, that 
is thrown down from salt-solution by acids is evidently a 
chemical compound of the original proteid with the acid 
(acid-proteid). 

Exp. 52.— Prepare a solution of vegetable casein from cnislied peas, 
alnionds, or pea-nuts, by soaking them tor some hours in warm water, 
to ■'vhich a few drop:? of dilute ammonia-water or potash-lye has been 
added, and alloAving the liquid to settle clear. Preeix3itate the casein 
by addition of an acid to the solution. 

The Chinese are said to prepare a vegetable cheese by 
boiling peas to a pap, straining the liquor, adding gypsum 
until coagulation occurs, and treating the curd thus ob- 
tained in the same manner as practiced with milk-cheese, 



9Q HOW CROPS GEOW. 

viz. : salting, pressing, and keej^ing until the odor and 
taste of cheese are developed. It is cheaply sold in the 
streets of Canton under the name of Tao-foo. Vegetable 
casein appears to occur in small quantity in the potato, 
and many plants ; and may be exhibited by adding a few 
drops of acetic acid to turnip) juice, for instance, which 
has been freed from albumin by boiling and filtering. 

The Globulins are insoluble in water, but dissolve in 
neutral salt-solutions. Some dissolve only in salt-solu- 
tions of moderate strength and are thrown down from 
these solutions by more salt. Others are soluble in sat- 
urated salt-solutions. Tliey are coagulated by heat. 
Some animal globulins may first be noticed. 

Vitellin is obtained from the yolk of eggs ; fat and 
pigment are first removed byetlier, and the white residue 
is dissolved in a solution of common salt (1 of salt to 10 
of water). Addition of water to the filtered solution 
separates the vitellin as a \;\liite, flocky mass. 

Paraglulullii exists in blood serum, and may be 
thrown down by saturating the serum with magnesium 
sulphate. It may be obtained in trnnspai-ent microscopic 
disks that are probably crystalline. Its solutions in biine 
coagulate by heat, lii-^e albumin. 

Fibrinogen. — When blood fresh from the veins of the 
horse is mixed directly with a saturated aqueous solution 
of magnesium sulphate, fibrinogen dissolves, and the 
liquid, after filtering from the red corpuscles, upon mix- 
ing with a saturated brine of common salt, deposits this 
body in white flocks, which unite to a tough, elastic 
mass. Its solutions in brine coagulate at a lower tem- 
perature than those of paraglobulin. 

Fresh-drawn blood, after standing a short time, coag- 
ulates of itself to a more or less firm clot. Under the 
microscope this process is seen to consist in the rapid 
formation of an intricate net-work of delicate threads or 
fibrils. These are fibrin, and come from the coagulation 



THE VOLATILE PART OF PLANTS. 97 

of fibrinogen. Coagulation hero appears to be induced 
by a ferment whose effect is suspended by strong saline 
solutions, but is renewed wiien these are mixed with 
much water. This ferment occasions decomposition of 
tlie fibrinogen, fibrin being one of the products. The 
fibrin-ferment is supplied from ruptured white blood - 
corpuscles. The chemical composition of fibrinogen and 
fibrin, as determined by analysis, is quite the same. 

Myosin. — Lean beef or other dead muscle-tissue, after 
mincing and washing with water to remove coloring mat- 
ters, is soaked in 10 per cent salt-solution. Myosin dis- 
solves and is precipitated from the filtered brine by diluting 
with water. It dissolves also in dilute hydrochloric acid 
and in dilute potash solution. Strong hydrochloric acid 
converts it into syntonin. Myosin does not exist in liv- 
ing muscle, but is formed after death, during rigor mor- 
tis, from the juices of the muscles by a process of coag- 
ulation. Its formation is accompanied by the develop- 
ment of lactic and carbonic acids. Myosin is the chief 
ingredient of what was formerly known as muscle-fibrin. 

Vegetable OloluUns occur abundantly in seods where 
they are chief ingredients of the so-called aleurone or 
protein-granules. From these j)i*otein-granules, or from 
the pulverized seeds, the globulins are extracted by salt- 
solutions and by weak alkalies. The globulin which 
water alone extracts from many seeds is dissolved by help 
of the salts, which are there present. Such saline ex- 
tracts are coagulated by heat and thus globulins have 
figured, no doubt, as ''vegetable albumin." Some glob- 
ulins are only known in the amorphous or granular state ; 
others occur as crystals. 

Conglutin exists abundantly, according to Eitthauson, 
in the seeds of peach, almond, lupin, radish, pea-nut, 
hickory-nut, and hazel-nut, where it is usually associated 
with legumin. It may be separated by weak brine, in 
which it is invariably soluble, while legumin, after sepa- 
7 



98 now CROPS grow. 

ration from alkali-soliitions, is undissolved by brine. The 
conglutin obtained from lupins and pea-nuts dift-ers some- 
what from that found in the hazel-nut, and in almond 
and peach seeds. Conglutiu cannot be crystallized from 
salt-sohitions, as readily ha])pens with vegetable vitellin. 

Vegetable Vitellin. — Applying this designation to al- 
buminoids which are insoluble in water, but dissolve in 
saturated salt-solutions, and are thence precipitated by 
water, we find vitellin more or less abundantly in seeds 
of squash, hemp, sunflower, lupin, bean, pea. Brazil-nut, 
castor-bean, and various other plants. It may be extracted 
from squash seeds by common-salt-solution (of 10 por 
cent) or dilute alkali. Diluting the brine with water or 
neutralizing the alkali with acids precipitates the vitellin, 
which, after washing with water, alcohol and ether, may 
be obtained in crystals (microscopic octahedrons) by dis- 
solving in warm brine and slowly cooling. From seeds 
of hemp and castor-bean Ritthausen obtained crystals 
identical in a2:>pearance and composition with those of 
squash seeds, but soluble in water, probably because of 
the presence of alkali salts. 

VegetaUe Myosin. — Weyl and Bischof consider that 
cereal and leguminous seeds contain or yield myosin anal- 
ogous to muscle-myosin, which differs from vitellin (and 
conglutin) in being preci|)itated from its solution in weak 
brine by saturating the same with Fait. They find that 
wheat-flour contains but little if any proteid besides 
myosin, and that when this is removed from the flour by 
salt-solution or by very weak soda-lye or by hydrochloric 
acid of 0.1%, the residue is incapable of yielding gluten. 
Gluten is therefore a decomposition-product of myosin. 
These results are confirmed by the recent work of Mar- 
tin {Jour, of Physiology, 1S87). Zoeller found that the 
pulp of potatoes, after starch and soluble matters had 
been removed by copious washings with water, yielded to 
10% salt-colution an albuminoid which separated when the 



THE VOLATILE PART OF PLANTS. 99 

brine was satiira,tod by addition of salt in excess. He also 
precipitated myosin from the juice of the tubers by sat- 
urating it with salt. 

The myosins are precipitated byconversion into allmli- 
proteids, when their brine-solutions are deprived of salt 
by dialysis or when these solutions are kept for some 
hours at 100° F. {Sidney Martin.) 

VegetaUe Paraglohulin is recently stated to exist in 
papaw-juice, and in the seeds of lequirity, Ahrus preca- 
tor ills. It is distinguished from myosin by requiring a 
higher temperature for coagulation from salt-solutions 
and in not suffering conversion into an insoluble alkali- 
proteid by dialysis or long heating to 100° F. {Martin.) 

Acid-Proteids are bodies formed from proteids by tlie 
prolonged action of acids. They are insoluble in water, 
alcohol and brines, but easily soluble in dilute acids or 
alkalies, and are precipitated by neutralizing these solu- 
tions. The solutions of acid-proteids in acids are not co- 
agulable by heat. The albumins and globulins are grad- 
ually concerted into acid-proteids by cold, highly dilute 
acids, and more rapidly b}^ stronger acids and gentle heat. 
Syntonm is the acid-proteid resulting from solution of 
muscle-flesh, or myosin, in weak hydrochloric acid, and is 
thrown down when the solution is neutralized by an 
alkali, as a white gelatinous substance. Acid-proteids 
may exist in seeds such as the oat, lupin, pea, bean, etc., 
which contain so much free acid, or acid salt, that the 
water extract is strongly acid to test-papers. 

Alkali-Proteids, or Albuminates. — The action of 
dilute alkali-solutions on most proteids converts them 
into bodies wliicli, like acid-proteids, are insoluble in 
water and salt-solutions, but soluble in dilute acids and 
alkalies, and are thrown down from these solutions by 
neutralization. Dilute acids do not convert them into 
acid-proteids. Alkali-proteids are said to exist gener- 
ally in the young cells of the animal, and may also occur 



100 HOW CROPS GEOW. 

in plants in the alkaline juices of the cambium. The 
"vegetable caseins," viz., legumin and gluten-casein, as 
they occur in the alkaline juices or extracts of plants, 
are probably bodies of this class, and when precipitated by 
acids unite to the hitter, forming compounds with an 
acid reaction. Casein of milk has been by some consid- 
ered to be an alkali-proteid, but is probably distinct. 

Proteoses and Peptones. — These terms designate 
bodies that result from tlie chemical alteration of albu- 
minoids, under the influence of "^'ferments" which exist 
in plants, but which have been most fully studied as they 
occur in the digestive apparatus of animals. 

The albuminoids, as found in plants, are mostly insol- 
uble in the vegetable juices, and those which are soluble 
(probably because of the presence of salts, acids or alka- 
lies) are mostly incapable of freely penetrating the cell- 
membranes which inclose them, and cannot circulate in the 
vegetable juices, and likewise, when they become the food 
of animals, cannot leave the alimentary canal so as to be- 
come incorporated with the blood until they have been 
chemically changed. During tfie processes of animal 
digestion the albuminoids of whatever kind undergo solu- 
tion and conversion into bodies which are freely soluble 
in water, and rapidly penetrate the moist membranes of 
the intestines, and thus enter into the circuhitiouo These 
bodies have been prepared for purposes of study by a 
partly artificial digestion, carried on in glass vessels with 
help of the digestive ferments obtained from the stomach 
(pepsin) or pancreas (trypsin) of animals.* 

It appears from Klihne and Chittenden's investigations 
that a series of soluble and diffusible products are formed 
from each albuminoid with progressive diminution of 
carbon and increase of oxygen, and, in some cases, of 
nitrogen. The first-formed products are termed pro- 



* Reference may be had to Chittenden's Studies in rhysiological 
Chemistry, Connecticut Acad., Vols. II and III, 1887 and 1880. 



THE VOLATILE PART OF PLANTS. 101 

teoses {aWumoses, caseoses, glohuloses, etc.) ; those last 
produced they designate i^e^Jtoiies, but investigators are 
not as yet agreed as to the precise application of these 
terms. What have been formerly called peptones are 
now considered to be largely proteoses. 

The composition of some of these bodies may be seen 
from the following analyses by Chittenden and Painter : 

C. H. N. S. O. 

Casein 53.30 7.07 15.91 0.82 22.03 

Protocaseose 52.50 7.15 15.73 0.96 23.86 

Deuterocaseose 51.59 6.98 15.73 0.75 25.03 

Casein-Peptone 49.94 6.51 10.30 0.68 26.57 

Of the several products which have been analyzed and 
classed as proteoses and peptones, it is not certain that 
any one is a strictly homogeneous substance. It is more 
than probable that some of them are mixtures. The 
proper use of these names is provisional, to characterize 
certain evidently distinct stages of albuminoid metamor- 
phosis, whose exact nature can only be cleared up by 
further investigation. 

The peptones may be defined as the final products of 
the action of the peptic ferment. 'J'hey are soluble in 
water and freely diifusible through animal membranes. 
The albumosos (or proteoses) are intermediate between 
the albuminoids and the peptones, being mostly soluble 
in water but not freely diffusible. 

The proteoses much resemble the albuminoids from 
which they are derived, not only in composition, but in 
many of their properties. The peptones have less re- 
semblance, but appear capable of partially reverting to 
proteoses, as some of the latter are said to yield coagula- 
ble albuminoids when kept in the moist state. 

Weak acids and alkalies also convert the albuminoids 
into proteoses and peptones, and probably the acid-pro- 
teids, perhaps also the alkali-proteids, already mentioned, 
contain proteoses in admixture. Since pejosin-digestion 
requires the aid of a free acid and trypsin-digestion sue- 



102 now CROPS GROW. 

coeds best in presence of a free alkali, the conditions 
under wliicli the joroteoses of digestion arc formed are in 
part identical with those that give rise to the acid-pro- 
teids and alkali-proteids. 

Peptones have been found in small proportions in the 
water-extract of various plants, e. g., seedlings, lujuns, 
barley-malt, young grass, alfalfa, etc. (Vs. St., XXIV, 
363, 371, 410, and XXXII, 389.) 

Vines has found a proteose in considerable quantity in 
the seeds of lupin, peony, and wheat and in the Brazil- 
nut and castor-bean, and considers bodies of this class to 
be of general occurrence in the protein-granules of plants. 

The proteose (hemialbumose*) from lupins has, exclu- 
sive of 0.81 p. c. of ash, the following composition per 
cent according to Vines : 



c. 


H. 


N. 


S. 


O. 


52.58 


7.24 


14.87 


1.52 


23.79 



Sidney Martin reports the existence of a proteose 
(hemialbumose) in the juice of the papaw or melon 
tree {Carica xmpaya) where it is associated with the fer- 
ment papain, which is very similar to that of the pan- 
creatic secretion of animals. 

Ferments are substances which produce or excite 
chemical changes in a manner as yet mostl}' unexplained, 
the ferments themselves not appreciably contributing of 
their own substance to the products of the processes 
which they set in operation. 

The ferments that figure in agricultural chemistry are 
closely related to and apparently derived from the albu- 
minoids, but in no case has their chemical composition 
been positively established. They are distinguislied and 
characterized almost solely by the sources wlienco they 
are derived, and the effects which they proluce. The 



*Ku]iiie first rtistingiiishorl the products of pepsin or trypsin diges- 
tion into lieniialbuniose ;ind nntiaUnimose, the foinier being converted 
by trypsin into anii(h)-a('ids (s(^e p. Hi), tlie latter remaining unaltered 
by the digestive ferments. KUlme & Chittcndon have nun-e recenlly 
shown "hemialbumose" to be a mixture mainly of prolo and den'.ero- 
albumose. 



THE VOLATILE PART OF PLANTS. 103 

substances which the chemist can prepare, and to which 
he gives special designations, are doubtless mixtures, and 
in most cases contain but a small proportion of the real 
ferment, which, in a state of entire purity, is unknown. 

Leaven, or Yeast, which has been employed in mak- 
ing bread, wire and beer for many centuries, contains, or 
mainly consists of, a microscopic plant of very simple 
structure (pp. 244-5), which, when placed in a solution of 
cane-sugar, is able in the first place to cause the 'Mnvor- 
sion" of that substance into the two sugars, dextrose and 
levulose, and, secondly, to transform both the latter into 
alcohol and carbon dioxide. The ^^invertinsj" effect of 
yeast upon cane-sugar has been traced to a substance 
which can be separated from the yeast and obtained as a 
dry, white powder. The alcoholic fermentation requires 
the living yeast plant for its accomplishment. Ferments 
are accordingly divided into the two chisses, unorganized 
and organized. We shall here notice briefly a few unor- 
ganized ferments or enzymes, as they are also termed, 
that have been somewliat carefully studied. 

Inverti?i is obtained from dry, pulverized yeast by 
heating it to 212° to coagulate albumin and then ex- 
tracting with warm water. The invertin dissolves, and, 
by addition of alcohol, is precipitated. Barth thus ob- 
tained a substance containing 6 per cent of nitrogen 
which was able, in the course of 48 hours, to transform 
(invert) 760 times its weight of cane-sugar. Invertin 
has no effect on starch or dextrin. 

Diastase is the name applied to a substance that may be 
obtained as a whitish powder from sprouted barley (malt) 
by extracting with dilute alcohol and precipitation with 
strong alcohol, which is capable of transforming 2,000 
times its weight of starch, first into dextrin and finally 
into maltose and dextrose. The purest diastase prepared 
by Lintner contained 10.4 per cent, nitrogen and gave 
reactions for albuminoids, but it had properties besides 



104 HOY/ CROPS GROW. 

its action on starch that strikingly distinguished it from 
the ordinary proteids. 

Pepsin is that ferment of the so-called gastric jnice of 
the animal stomach which enahles this organ to dissolve 
and ^* peptonize" the albuminoids of the food. It may 
be extracted from the inner coating of the stomach by 
gl^^cerine or very dilute hydrochloric acid, and is precip- 
itable from these solutions by strong alcohol. Pepsin 
requires the presence of a free acid to dissolve the albu- 
minoids ; in neutral or alkaline solution it has no *' di- 
gestive power." 

Trypsin is a ferment formed in the pancreas and exist- 
ing in the pancreatic juice which, in mammalian animals, 
during the digestion of food, is poured into the upper 
intestine, where it continues and completes the solution 
of albuminoids begun by the gastric juice. Trypsin acts 
in neutral but most effectively in alkaline solutions ; its 
operation is arrested by free acids. The results of its 
action differ in some respects from those of pepsin. 

Papain. — The milky juice of the Brazilian plant Car- 
ica papaya, or melon-tree, contains this ferment, which, 
like trypsin, is freely soluble in water, rapidly dissolves 
albuminoids, best in neutral or alkaline solutions, convert- 
ing them into proteoses and peptones. Papain itself, as 
obtained by Wurtz & Bouchut, has the properties and 
composition that characterize the proteoses. 

Ferments appear to perform very important functions 
in the vegetable as well as in the animal organism, and 
have to be referred to frequently as occasioning the con- 
version of insoluble into soluble substances, and of com- 
plex into simpler bodies. 

Composition of the Albuminoids. — There are va- 
rious reasons why the exact compocition of some of the 
bodies just described is still a subject of uncertainty. They 
are, in the first place, naturally mixed or associated with 
other matters from which it is very difficult to separate 



THE VOLATILE PART OE PLAKTS. 105 

them fnllj. Again, if we succeed in removing foreign 
substances, it must usually be done by tlie aid of acids, 
alkalies, salt-solutions, alcohol and ether, and there is 
reason to believe that in many cases these reagents essen- 
tially modify the properties and composition of the pro- 
teids. These bodies, in fact, as a class, are extremely 
susceptible to change and alter in respect to appearance, 
solubility, and other qualities that serve to distinguish 
them, without any corresponding change in chemical 
composition being discoverable by our methods of anal- 
ysis. On the other hand, the substances that have been 
prepared by difi'erent experimenters from the same 
sources, and by substantially the same methods, often 
show decided differences of comj^osition. 

Finally, the methods of analysis used in determin- 
ing their composition are liable to considerable error, 
and, if applied to the pure substances, are scarcely 
delicate enough to indicate their diuerences with entire 
accuracy. 

In the accompanying table (p. 106) are given the most 
recent and trustworthy analyses of the various vegetable 
albuminoids, and of the corresponding substances of ani- 
mal origin. 

Referring to the analyses of Albumins we observe that 
the egg-albumin differs from serum-albumin in contain- 
ing about one per cent more of oxygen and one less of 
carbon, while hydrogen, nitrogen and sulphur are prac- 
tically the same. These two albumins have been very 
thoroughly studied, their difference of composition is 
well established, and they have positive differences in 
their properties, so that there can be little doubt that 
they are specifically distinct substances. Of the Vegeta- 
ble Albumins none offer any reasonable guarantee of 
purity. The composition of barley-albumin is near that 
of the animal albumins, but it contains one-third less 
sulphur. So far, then, as present data indicate, the veg- 



106 



HOW CROPS GROW. 



COMPOSITION OF ALBUMINOIDS. 



ALBUMINS. 



Ess 52.2 

131, )od serum ;53.1 

AHieat '53.1 

Barley '52.8 



FIBRINS. 



Blood 

Gluten-fibrin, wheat. 
" " maize . 

CASEINS. 



52.7 
54.3 
54.6 



Milk casein* |53.3 

Gluten-cafiein, wheat 52.9 

" " " 52.8 

Gluten-casein, buckwheat*. 50.2 
Legumin, lupins 51.4 



GLOBULINS. 



Paraglobulin 52. 7 

Fibrinogen, blood '52.9 

Myosin, beef 52.8 

Conglutin, lupin 50.1 

" hazel-nut 51.2 

Vitellin, sqiiash .51.3 

" hemp (cry.stals) 51 . 

" Brazil-nut 52.4 



Gliadin, wheat. 



G.9 
0.9 



</5 



15.8 1.9 23.2 
16.0 1.8 22.2 



Analysts. 

Chittenden & Folton. 
llammarsttni. 



?:2l5:8}:2 23:S k^i"^^^"^^^"- 



6.8 16.9 1.1 22.5 



Hammarsten. 



.2 16.9 1.0 10. G 



7.5 15.5 0.7 £1.7 



7.1 15.9 0.8 22.0 
7.0 17.1 1.0 22.0 
7.0 15.8 1.1 23.3 
6.8 17.4 1.5 24.1 
7.017.5 0.623.5 



r. > Rittliausen. 



Chittenden & Painter. 
Rittliausen. 
Chittenden & Smith. 

Rittliausen. 



J ■ o Jr ■ - M oil ■ o } Hammarst en . 
0.9 Ifa. r 1.3 22.2 I 

7.1 16.8 1.3 21.9 Chittenden & Cummins. 

7.0 18.7 1.1 23.0 1 

7.118.6 0.622.5 iRitthausen 

7 . 5 18 . 1 . 6 ' 22 . 5 f ^^"t 'i^^^^en . 

7.0 18.7 0.8 22.5 j 
7.118.10.5 21.9, Weyl. 

7.1 18.0 0.9 21.3; Rittliausen. 



MUCEDIN, wheat 54.1 6.9 16.6 0.9 21.5' Rittliausen. 

See pp. 101 and 102 for analyses of Proteoses and Peptone. 

etablc albumins are not identical with those derived from 
the animal. 

As respects the Fibrins we have already seen that tlcre 
is no similarity in properties between that of blood and 
those obtained from gluten. The analyses of tlie tv/o 
gluten-fibrins show either tliat these substances are quite 
distinct or that they have not yet been obtained in the 
pure state. 

The Vegetable Caseins, as analyzed by Eitthausen, are 



* The analysis of milk casein should include 0.9 ])li()si>li<)rus. The 
buckwheat casein contained 0.9 i)li()sphorus, which is not incIudiHl in 
the analysis. Whetlu^r })hosph()riis is an iiiiindieiit of casein, or an 
"impurity," is Lot perhaps i)ositively established. 



THE VOLATILE PAliT OF PLANTS. 107 

observed to contain more nitrogen by 1.2 to l.G per cent 
than exists in animal casein. Furthermore, they differ 
from eacli other so widely in cai'bon content (2.7 percent) 
as to make it highly probable that their true composition 
was not in all cases correctly determined. 

This conclusion is justined by the results of Chittenden 
& Smith, who have recently analyzed five different prep- 
arations of gluten-casein, made from wheat by Ritthau- 
sen's method. The average of their accordant analyses 
is given above.* Since nitrogen was determined by two 
methods (those of Dumas and KJeldahl) these analyses 
would appear to establish the composition of gluten- 
casein, which accordingly closely agrees with that found 
by Eitthausen for "albumin" from barley, and with 
that of paragl(;bulin, and has the same nitrogen content 
as the casein of milk. 

The Animal Globulins agree in composition with each 
other as well as with animal fibrin which is formed from 
globulin (fibrinogen). The Vegetable Globulins are strik- 
ingly different in composition, containing 1.5 to 2 per 
cent more nitrogen and mostly but half as much sul- 
phur. The hazel-nut conglutin and the hemp-seed vitel- 
lin have the same composition. 

It is evident that the vegetable albuminoids, on the 
whole, are distinct from those of the animal, but their 
true composition and relations to each other, to a great 
extent, remain to be established. 

Some Mutual Relations of the Albunimoids. — It was 
formerly sup})osed that these bodies are ideiitical in com- 
position, the differences among the analytical results 
being due to foreign matters, and that they differ from 
each other in the same way that cellulose and starch 
differ, viz.: on account of different arrangement of the 
atoms. Aftei'wards, Mulder advanced the notion that 
the albuminoids are compounds of various proportions 

*KnKlly communicated by the authors. 



108 HOW CROPS GROW. 

of hypothetical suljihiir and jihosiihorus radicles with 
a common ingredient, which he termed protein (from 
the Greek signifying *' to take the first place," because 
of the great physiological importance of such a body). 
Hence the designations protein-bodies and proteids. 
The transformations which these substances are capable 
of undergoing sufficiently show that they are closely 
related, without, however, satisfactorily indicating in 
what manner. 

In the animal organism, the albuminoids of the food, 
of whatever name, are dissolved in the juices of the 
digestive organs, and pass into the blood, where they 
form blood albumin and globulin. As the blood nour- 
ishes the muscles, they are modified into the flesh-albu- 
minoids ; on entering the mammary system they are 
converted into casein, while in the appropriate part of 
the circulation they are formed into the albumin of the 
egg, or embryo. 

In the living plant, similar changes of place and of 
character occur among these substances. 

TJie AlbumimAiU in A7iimal Nutrition. — We step 
aside for a moment from our proper plan to direct atten- 
tion to the beautifid adaptation of this group of organic 
substances to the nutrition of animals. Those bodies 
which we have just noticed as the animal albuminoids, 
together with others of similar composition, constitute 
a large share of the healthy animal organism, and espec- 
ially characterize its actual working machinery, being 
essential ingredients of the muscles and cartilages, as 
well as of the nerves and brain. They likewise exist 
largely in the nutritive fluids of the animal — in blood 
and milk. So far as we know, the animal body has not 
the power to produce a particle of albumin, or fibrin, or 
casein except by the transformation of similar bodies pre- 
sented to it from external sources. Th-e^y arc hence indis- 
pensable ingredients of the food^ of^^animals, and__were 



THE VOLATILE PART OF PLANTS. 100 

therefore designated by Liebig as the plastic elements of 
nutrition. They have also been termed the blood-build- 
ing or muscle-forming elements. It is, in all cases, the 
plant which originally constructs these substances, and 
places them at the disposal of tlie animal. 

The albuminoids are mostly capable of existing in the 
liquid or soluble state, and thus admit of distribution 
throughout the entire animal body, as in blood, etc. They 
likewise readily assume the solid condition, thus becom- 
ing more permanent parts of the living organism, as well 
as capable of indefinite preservation for food in the seeds 
and other edible parts of plants. 

Complexity of Constitution, — The albuminoids are 
highly complex in their chemical constitution. This fact 
is shown as well by the multiplicity of substances which 
may be produced from them by destructive and decom- 
posing processes as by the ease with which they are 
broken up into other and simpler compounds. Kept in 
the dissolved or moist state, exposed to warm air, they 
speedily decompose or putrefy, yielding a large variety of 
products. Heated with acids, alkalies, and oxidizing 
agents, they mostly give origin to the same or to anal- 
ogous products, among which no less than twenty differ- 
ent comj^ounds have been distinguished. 

The numbers of atoms that are associated in the mole- 
cules of the proteids are very great, though not in most 
cases even approximately known. The Haemoglobin of 
blood, which forms red crystals that admit of preparing 
in a state of great purity, contains in 100 parts — 



c 


H 


N 


O 


S 


Fe 


54.2 


7.2 


16.1 


21.6 


0.5 


0.4 



The iron (Fe) is a constant and essential ingredient, and 
if one atom only of this metal exist in the haemoglobin 
molecule, its empirical formula must be something like 
C64oHioooNi64FeS20i9o, aud its molecular weight over 14,- 
000. Haemoglobin readily breaks up into a proteid and a 



no 



now CKO L'o GKOW. 



much simpler ved ci'jst'dlVme substance, Ilaemaeel in, yield- 
ing about 9G per cent of the former and 4 per cent of 
the latter. Haematin has approximately the formula 
OssHgiNiFeOs, so that the proteid, though simpler than 
haemoglobin, must have iin extremely complicated mole- 
cule, and it is, accordingly, difficult to decide whether a 
few thousandths of the acids, bases or salts which may 
be associated with these bodies, as they exist in i)lants or 
pass through the hands of the chemist, are accidental or 
essential to their constitution. 

OccurrG7ice 171 Plants. — Aleurone. — It is only in the 
old and virtually dead parts of a living plant that albu- 
minoids are ever wanting. In the young and growing- 
organs they are abundant, and exist dissolved in the sap 
or juices. They are es})ecially abundant in seeds, and 
here they are often deposited in an organized form, chiefly 








*30CDOOI' 



r!Ii|n 






Fi-. 19. 




in grains simiUir to those of starch, and mo.stly insoluble 
in water. 

'^I'liose grains of al])riminoid matter are not, in many 
cases at least, juire albuminoids. Hartig, who first de- 
scribed them minutely, has distinguished them by the 
name aleurcme, a term which we may conveniently em- 
ploy. By the word aleurone is not meant simply an 



THE VOLATILE PAKT OF PLANTS. 



Ill 



albuminoid, or mixtiiro of albuminoids, but the organ- 
ized granules found in the plant, of which the albumin- 
oids are chief or characteristic ingredients. 

In Fig. 18 is represented a magnified slice throngli the 
outer cells (bran) of a huriked o it kernel. The cavities 
of these outer cells, a, c, are chiefly occupied with very 
fine grains of aleurone. In one cell, l, are- seen the 
miich larger starch grains. In the interior of the oat 
kernel, and other cereal seeds, the cells are chiefly occu- 
pied with starch, but throughout grains of aleurone arc 
more or less intermingled. 

Fig. 19 exhibits a section of the exterior part of a 
flax-seed. The outer cells, a, contain vegetable muci- 
lage ; the interior cells, e, are mostly filled with minute 
grains of aleurone, among which droplets of oil, /, are 
distributed. 




r?-) 






Fiir. 20. 



In Fig. 20 are 
shown some of the 
forms assumed by in- 
dividual albuminoid- 
grains ; a is aleurone 
from the seed of the vetch, h from the castor-bean, c 
from flax-seed, d from the fruit of the bayberry {Myrica 
cerifera) and e from mace (an appendage to the nutmeg, 
or fruit of the Mgristica moscliata). 

Crystalloid aleurone. — It has been already remarked 




Fiff. 21. 



that crystallized albuminoids exist in plants. This was 
first observed by Hartig (Fntwickelungsgeschichte des 



112 now CROPS GROW. 

PJlanzenTceims, p. 104). In form they sometimes imitate 
crystals quite perfectly, Fig. 31, a; in other cases, h, 
they are rounded masses, having some crystalline planes 
or facets. They are soft, yield easily to pressure, swell 
up to double their bulk when soaked in weak acids or 
alkalies, and their angles have not the constancy peculiar 
to ordinary crystals. Therefore the term crystalloids, i. e., 
having the likeness of crystals, has been applied to them. 

As Oohn first noticed \j our. far Praht. Ghem., 80, p. 
129), crystalloid aleurone may be observed in the outer 
portions of the potato tuber, in which it invariably pre- 
sents a cubical form. It is best found by examining the 
cells that adhere to the rind of a potato that has been 
boiled. In Fig. 21, a represents a cell from a boiled 
potato, in the center of which is seen the cube of aleurone. 
It is surrounded by the exfoliated remnants of starch- 
grains. In the same figure, h exhil)its the contents of a 
cell from the seed of the bur rood [Sparr/aniurn ramo- 
sum), a plant that is common along the borders of ponds. 
In the center is a comparatively large mass of aleurone, 
having crystalloid facets. 

As already stated, the proteids in the crystalloid alen- 
rones of hemp, castor-bean and squash have the chemical 
characters of globulin. The aleurone of the Brazil-nut 
(BerthoUetia) and that of the yellow lupin contain, ac- 
cording to Hartig and Kubel, 9.4% of nitrogen which 
corresponds to some 50 or 60% of proteids. 

AVeyl obtained from the Brazil-nut a very pure amor- 
phous vitellin with 1 8. 1 % of nitrogen. Tiie vitellin of 
Brazil-nut, castor-bean, and of hemp and squash seeds has 
been recrystalized from salt solutions by Schmiedeberg, 
Drechsel, Grilbler and Eitthausen. According to Vines, 
seeds of lupin and peony yield a myosin to salt-solution, 
and sunflower seeds, after treatment with ether to remove 
oil, yield a globulin with the properties of myosin, but if 
alcohol is used, the proteid has the character of vitellin. 



THE VOLATILE PART OF PLANTS. 113 

Vines, who has examined the aleurone of many plants, 
finds it in till cases more or less soluble in water. The 
globulin doubtless goes into solution by help of the salts 
present. Vines also states that a body soluble in water, 
having the properties of a proteose {hemialbumose) , is 
universally present in aleurone. 

Edimatioii of the Albmninoids.— The quantitative sep- 
aration of these bodies, as they occur in plants, is mostly 
impossible in the present state of science. In many cases 
their collective quantity in an organic substance may be 
calculated with approximate accuracy from its content of 
nitrogen. 

In calculating the nutritive value of a cattle-food the 
albuminoids are currently reckoned as equal to its nitro- 
gen multiplied by G.25. This factor is the quotient ob- 
tained by dividing 100 by 16, which, some 25 years ago, 
when cattle-feeding science began to assume its present 
form, there was good reason to assume was the average 
per cent of nitrogen in the albuminoids. As Ritthansen 
has insisted, this factor is too small, since the albuminoids 
of the cereals and of most leguminous seeds, as well as of 
the various oil-cakes, contain nearer 17 than IG per cent 
of nitrogen, if our analyses rightly represent their com- 
position, and the factor 6 (= 100 -f- 16. 6G) would be 
moie nearly correct. 

This mode of calculation only applies with strictness 
where all the nitrogen exists in albuminoid form. This 
appears to be substantially true in most seeds, but in case 
of young grass and roots there is usually a considerable 
proportion of non-albuminoid nitrogen, for which due 
allowance must be made. (See Amides.) * 

* Ammonia, NH,, and Nitric acid, NHO3. These bodies are mineral, not 
oreanie substances, and are not, on the whole, considerable ingredients 
of plants. They are however the principal sources of the nitrogen of 
vegetation, and, serving as plant-food, enter plants through their roots, 
chiefly from the soil, aiid exist within them in small quantity, and for 
a time, pending the conversion of their nitrogen into that of the 
amides and albuminoids, to whose production they are probably 
essential. In seeds and fruits, and in mature plants, growing m soils 



114 HOW CROrS GROW. 

AVERAGE QUANTITY OF ALr.UMINOIDS IN VARIOUS VEGETABLE 
PRODUCTS.— ALBUMINOIDS = N X C.25. 

American, Jenkins. German, Wolff. 

Maize fodder, green 1.8 1.9 

Beet tups, " 2.7 3.0 

Carrot tops, " 4.3 5.1 

Meadow grass, in bloom 3.1 4.8 

Red clover, " 3.7 4.8 

White clover, " 4.0 5.G 

Turnips, fresh 1.1 1.8 

Carrots, " 1.1 2.2 

Potatoes, " 2.2 3.4 

Corn cobs, air-dry 2.3 2.3 

Straw, " 3.5 4.0 

Pea straw, " 7.3 10.4 

Bean straw, «' 10.2 1(5.3 

Meadow hay, in bloom 7.0 15.5 

Red-clover hay, " 12.5 l!).7 

Wliite-clover hay, " .14.fi 23.2 

Buckwheat kernel, air-(h-y 10. 14.4 

Barley " " .'.......12.4 IG.O 

Maize " " lo.G 10.0 

Rye " " lo.G 17.G 

Oat " " 11.4 17.G 

Wheat " " 11.8 20.8 

Pea •♦ " 22.4 3.5.8 

Bean " " 24.1 40.8 

/ TirE Amides, Amidoacids, Imides, akd Amines. 
— Ammoniii {iiid the ammonium salts, so important as 
food to plants, and as ingredients of the atmosphere, of 
soils, and of manures, occur in so small proportions in 
living vegetation as to scarcely require notice in this 
work occupied Avitli tlie composition of Plants. They 
are^ however, important in connection with the amides 
now to be briefly described. Ammonia, an invisible gas 
of pungent odor which dissolves abundantly in water to 
form the aqua ammonia of spirits of hartshorn of the 
apothecary, is a compound of one atom of nitrogen with 
three atoms of hydrogen. It unites to acids, forming 
the ammonium salts : 



of moderate fertility, both ammonia and nitric acid, or strictly speak- 
ing, ammonia-salts and nitrates, commonly occur in very small jiro- 
portions. In roots, stems, and foliage of plants situated in soUs rich 
in these substances, they may be jn-esent in notable quantity. The 
dry leaves and stems of tobacco and beets sometimes contain several 
percent of nitrates. When these substances are presented to plants in 
abundance, especially in dry Aveatlier, they may accumulate in the 
roots and lower parts of the plant more rapidly than they can be assim- 
ilated. On the other hand, when their sui:)ply in the soil is relatively 
small they are so completely and rapidly assimilated as to be scarcely 
detectable. Their i^ossible iiresence should be taken into accxmnt when 
it is undertaken to calculate the albuminoids of the plant from the 
amount of nitrogen fourid in its analysis. 



THE VOLATILE TART OF PLANTS. llf) 

CIT3COOH + NH3 = CH3COONH4 

Acetic acid. Ammonia. Amm,omam acetate. 

Amides. — This term is often used as a general desig- 
nation for all the bodies of this section which result from 
the substitution of the hydrogen of ammonia by any 
atom or group of atoms. In a narrower sense amides 
are those ammonia-derivatives containing ^'acid-radi- 
cals " which are indicated in their systematic names. 

Acetamide, OHgCONHo. Many ammonium salts, 
when somewhat strongly heated, suffer decomposition 
into amides and water. 

CH3COONH4 = CH3CONH2 + HjO 

Ammonium acetate. Acetamide. Water. 

The above equation shows that acetamide is ammonia, 
NIT3, or IINIIo, one of whose hydrogens has been re- 
placed by the group of atoms. CH3CO, the acetic acid 
radical, so called. Acetamide is a white crystalline body. 
The simple amides, like acetamide, are as yet not known 
to exist in plants. They readily unite with water to 
produce ammonium salts. 

Carbamide, or Urea C0(NH2)2. This substance — 
the amide of carbonic acid 00(011)2 — naturally occurs 
in considerable proportion in the urine of man and mam- 
malian animals. It is a white, crystalline body, with a 
cooling, sliglitly salty taste, which readily takes up the 
elements of water and passes into ammonium carbonate. 
Urea has not been found in j^lants, but derivatives of it 
in which acid radicals replace a part of its hydrogen are 
of common occurrence. (Gnanin, allantoin.) 

A7nidoacids are acids containing the NHo group as a 
part of the acid radical. 

Amidoacetic Acid, CoH^NOo, or CH2(NHo)000H, 
is derived from acetic acid, OH3COOH, by the replace- 
ment of H in CH3 by NIIo. The amidoacids have not a 
sour, but usually a sweetish taste, and, like the amides, 
act botli as weak acids and weak bases. Amidoacetic 



IIG HOW CROPS GROW. 

acid, also called glycocoll, lias not as yet been found in 
plants, but exists in the scallop and probably in other 
shell-fish, and a compound of it, benzoylglycocoll or liip- 
puric acid, is a nearly constant ingredient of the urine of 
the horse and other domestic herbivorous, animals. 

Betain, or trimethylglycocoll, CsIInNOg, a crystalliza- 
ble substance found in beet-juice, stands in close chem- 
ical relations to amidoacetic acid. 

Amidovaleric acid, CsHn^Oo, occurs in ox-pancreas 
and in young lupin plants. Amidocaproic acid, or 
Leucin, C6H13NO2, first observed in animals, has lately 
been discovered in various plants. The same is true 
of Tyrosin, or oxyphenyl-amidopropionic acid, 
CglluNOg, and of phenyl - amidopropionic acid, 
CJInNO^. 

The above amidoacids are readily obtained as products 
of decomposition of animal and vegetable albuminoids by 
the action of hot acids. Amidoacetic acid was thus first 
obtained from gelatin. Leucin and Tyrosin are com- 
monly prepared by boiling horn shavings with dilute sul- 
j^liuric acid ; they are also formed from vegetable albu- 
minoids by similar treatment and are final results of the 
digestion of proto- and deutero-proteoses (hemialbumose) 
under the action of trypsin and papain. 

Asparagin and Glutamin. — These bodies, which are 
found only in plants, are amides of amidoacids, being de- 
rived from dibasic acids. Asparagin, the amide of 
amidosuccinic acid, 

CH(NH,)COOH 

CH2CONH2 
has been found in very many plants, especially in those 
just sprouted, as in asparagus, peas, beans, etc. Aspara- 
gin forms white, rhombic crystals, and is very soluble in 
water. 

Glutamin, tbe amide of amidoglutaric acid, 

C H rNH ^/<"^^H, 

»-3^l5U>W2\COOH 



THE VOLATILE PART OF PLANTS. 117 

has been found, together with asparagin, in beet-juice 
and iu squash seedlings. 

The amides, when heated with water alone, and more 
easily in presence of strong acids and alkalies, are con- 
verted into ammonia and the acids from which they are 
derived. Thus, asparagin yields ammonia and amido- 
succinic acid at the boiling heat under the influence of 
hydrochloric acid, or of potassium hydroxide, and gluta- 
min is broken up by the last-named reagent at common 
temperatures, and by water alone at the boiling point, 
with formation of ammonia and amidoglutaric acid. 

The amidoacids are not decomposed by hot water or 
acids with separation of ammonia. Amidosuccinic and 
amidoglutaric acids result from albuminoids by boiling 
with dilute sulphuric acid, and by the action of bromine. 
The latter acid as yet has been obtained from vegetable 
albuminoids only, and is prepared most abundantly from 
gluten, and especially from mucedin. 

Imidcs, closely related to the amides, are a series of 
very interesting substances, into whose chemical consti- 
tution we cannot enter here further than to say that they 
contain several NH* groups, i. e., ammonia, NHg, in 
which two hydrogens are replaced by hydro-carbon, or 
oxycarbon groups or carbon atoms. 

These bodies are Uric acid, C5H4N4O3, Adcnin, C5H5N5, 
Guanin, C5H5N5O, Allantoin, C4H6N4O3, Xanthin, 
Hypoxantldn, C5H4N4O, Theobromin, C7H8O4O2, Caffein, 
C8H10N4O2, and Vernin, CicHsoNsOg. Of these the 
first, so far as now known, occurs exclusively in the ani- 
mal. Adenin, Guanin, Allantoin, Xanthin, and Hypo- 
xanthin, are common to animals and plants ; the last 
three are exclusively vegetable. 

Caffein exists in coffee and tea combined with tannic 
acid. In the pure state it forms white, silky, fibrous 
crystals, and has a bitter taste. In coffee it is found to 

* Or its hydro-carbon derivatives. 



118 now CRors grow. 

the extent of one-half per cent ; in tea it occurs in much 
larger quantity, sometimes as high as 6 per cent. 

Theobromin resembles caffein in its characters. It 
is found in the cacao-bean, from which chocolate is man- 
ufactured. 

Vernin, discovered recently in various plants, young 
clover, vetches, squash-seedlings, etc., yields guanin by 
the action of hydrochloric acid. All these bodies stand 
in close chemical relations to each other, being complex 
imiilo derivative? of dioxymalonic (mesoxalic) acid. 

The amides and amidoacids, like ammonia, are able to 
combine directly with acids, are accordingly bases, but 
they are weak bases, because the l)asic quality of their 
ammonia is largely neutralized by the acid radicals already 
l)resent in them. On the other hand, amides and ami- 
doacids often act as weak acids, for a portion of the hydro- 
gen of the NII2 group is easily disj^laced by metals. 

The amides thus in fact possess in a degree the quali- 
ties of both the acid and of the base (ammonia) from 
which they are derived. Thoy also are commonly *' neu- 
tral" in the sense of having no sharj) acid or alkaliuQ 
taste or corrosive character. 

In vegetation amides appear as intermediate stages be- 
tween ammonium salts and albuminoids. They are, on 
the one hand, formed in growing plants from ammo- 
nium salts by a constructive process, and from them or 
by their aid, probably, the albuminoids are built up. On 
the other hand, in animal nutrition they are stages 
through which the elements of the albuminoids pass in 
their reversion to purely mineral matters. In germinat- 
ing seeds and developing buds they probably combine 
both these offices, being first formed in the germ from 
the albuminoids of the seed, entering the young plant or 
shoot, and in it being reconstructed into albuminoids. 
Their free solubility in water and ability to penetrate 
moist membranes adapt them for this movement. They 



THE VOLATILE PART OF PLA:NTS. 119 

temporarily accumulate in seedliugs and buds, but disap- 
pear again as growth takes place, being converted into 
albuminoids, in whicii transformation they require the 
conjunction of carbbydrates. Their ability to unite with 
acid as well as bases further qualifies them to take part 
in these physiological processes. 

The imides are also at once weak bases and weak acids. 
Uric acid and allantoin, relatively rich in oxygen, have 
the acid qualities best developed. Guanin and cafiein, 
with less oxygen and more hydrogen, are commonly 
classed among the organic bases, as in them the basic 
characters are most evident. 

Amines. — When the hydrogen of ammonia is replaced 
by hydrocarbon groups (radicals) such as Methyl, CH3, 
Ethyl, C2H5, Phenyl, O0H5, etc., compoic7id ammonias ov 
amines result which often resemble ammonia in physical 
and chemical characters, and some of them appear to bo 
stronger bases than ammonia, being able to displace the 
latter from its combinations. 

TrimGUiylamine, N( 0113)3, may be regarded as ammo- 
nia whoso hydrogens are all substituted by the methyl 
group, CHg, and is a very volatile liquid having a rank, 
fishy odor, which may be obtained from herring pickle, and 
exhales from some plants, as from the foliage of Chenopo- 
dium vuIva7Ha, and the flowers of Crataegus oxycantlta. 
It is produced from lelain (trimethylamidoacetic acid), 
l)y heating with potash solution, just as ammonia is 
formed from many amides under similar treatment. 

Cliolin, C5H15NO2, and Neurin, C5H13NO, are organic 
bases related to trimethylamine, which were first ob- 
tained from the animal. Cholin Ig an ingredient of the 
bile, and is found also in the brain and yolk of eggs, 
where it exists as a component of lecithin. It has latterly 
been discovered in the hop, lupin and pumpkin plants, 
and in cotton seed ; by oxidation it yields betain. Neu- 
rin is readily formed from cholin by the action of alka- 



120 now CHOPS grow. 

lies and in the process of putrefaction. It is a \iolent 
poison, and is perhaps one of the ingredients which, in 
the seeds of the vetch and of cotton, prove injurious, or 
even fatal, when these seeds are too largely eaten by ani- 
mals. Cholin and Neurin are syrupy, highly alkaline 
liquids. 

7. Alkaloids is the general designation that has 
been applied to the organic bases found in many plants, 
which are characterized in general by their poisonous 
and medicinal qualities. Caffein and Theobromin, already 
noticed, were formerly ranked as alkaloids. We may 
mention the following : 

Nicotin, C10H14N2, is the narcotic and intensely poi- 
sonous princij^le in tobacco, where it exists in combina- 
tion with malic and citric acids. In the pure state it is 
a colorless, oily liquid, having the odor of tobacco in an 
extreme degree. It is inflammable and volatile, and so 
deadly that a single drop will kill a large dog. French 
tobacco contains 7 or 8 per cent ; Virginia, 6 or 7 per 
cent ; and Maryland and Havana, about 2 per cent of 
nicotin. Nicotin contains 17.3 per cent of nitrogen, 
but no oxygen. 

Lupinidin, CgHigN, Lupanin, CisHasNgO, and Lii- 
jiinin, C21H40N2O0, are bases existing in the seeds of the 
lupin. The lirst two are liquids ; the last is a crystal- 
line solid. They are poisonous and are believed to occa- 
sion the sickness wliich usually follows the use of lupin- 
seeds in cattle food. 

Sinajnn, C16H23NO5, occurs in white mustard. When 
boiled with an alkali it is decomposed, yielding neurin 
as one product. 

Vicin, CasHsiNiiOoi, and Conviciny C10H14N3O7, are 
crystalline bases that occur in the seeds of the vetch, with 
regard to whose nature and properties little is known. 

Ave?im, C56H21NO18, according to Sanson, is a sub- 
stance of alkaloidal character, existing in oats. It is said 



THE VOLATILE PART OF PLANTS. 121 

to be more abundant in dark than in liglit -colored oats, 
and, when present to the extent of more than nine-tenths 
of one per cent, to act as a decided nerve-excitant on ani- 
mals fed mainly on oats. Avenin is described as a gran- 
ular, brown, non-crystallizable substance, but neither 
Osborne (at tlie Connecticut Experiment Station) nor 
Wrampelmeyer {Vs. St., XXXVI, p. 299) have been able 
to find any evidence of the presence of such a body in oats. 

3Iorphin, C17H19NO3, occurs, together with several 
other alkaloids, in opium, the dried milky juice of the 
seed-vessels of the poppy cultivated in India. Its use in 
allaying pain and obtaining sleep and its abuse in the 
*^ opium habit" are well known. 

Piperin, C17II19NO3, the active principle of white and 
black pepper, is a white crystalline body isomeric with 
morphin. 

Qumin, O20II24N2O2, is the most important of several 
bases used as anti-malurial remedies obtained from the 
bark of various species of cinchona growing in the forests 
of tropical South America, and cultivated in India. 

Strychnin, C21II22N2O2, and Briicin, C23II26N2OII, is 
the intensely poisonous alkaloid of nux vomica (dog 
button). 

Atropin, C17II23NO3, is the chief poisonous principle 
of the ''Nightshade" or belladonna, and of stramonium 
or "Jamestown weed." - 

Veratrin, C32H4gN09, is the chief toxic ingredient of 
the common White Hellebore, so much used as an 
insecticide. 

Solanin, C42II87NO15 (?), is a poisonous crystalline 
alkaloid found in many species of Solanum, especially in 
the black nightshade (Solamim nigrum). It occurs in the 
sprouted tubers and green fruit of the potato (Solanum 
tulerosinn) and in the stems and leaves of the tomato 
{Solanum li/copersiciwi). 

The alkaloids, so far as investigated, appear to be more 



122 HOW CROPS GROW. 

or less complex derivatives of the bases Pyridm, CsHsN^ 
and Quinolui, CylljISr, which are colorless, volatile 
liquids with sharp, unpleasant odor, produced from albu- 
minoids at high temperatures, and existing in smoke, 
bone-oil and lar. The alkaloids bear to these bases simi- 
lar relations to those subsisting between the amines and 
ammonia. 

8. Phosphorized Suesta:n'CES. — This class of bodies 
are important because of their obvious lelations to the 
nutrition of the brain and nerve tissues of the animal, 
which have long been known to contain phosphorus as 
an essential ingredient. All our knowledge goes to show 
that phosphorus invariably exists in both plants and ani- 
mals as phosphoric acid or some derivative of this acid, 
or, in other words, that their phosphorus is always 
united to oxygen as in the phosphates, and is not directly 
combined to carbon, hydrogen, or nitrogen. 

Nuclein. — This term is currently employed to desig- 
nate various imperfectly-studied bodies that resemble the 
albuminoids in many respects, but contain several per 
cent of phosphorus. They are easily decomposable, 
boiling water being able to remove from them phosphoric 
acid, and under the action of dilute acids they mostly 
yield phosphoric acid, albuminoids and hypoxanthin, 
C5II4N4O, or similar imide bases. They are very difficult 
of digestion by the gastric juice. The nucleins are found 
in the protoplasm and especially in the cell-nuclei (see 
]). 245), of both plants and animals, and have been ob- 
tained from yeast, eggs, milk, etc., by a process based on 
tlieir indigestibility by pepsin. Chemists are far from 
agreed as to the nature or composition of the nucleins. 

Lecithin, C44TT.J0NPO.). — This name applies to a num- 
ber of substances that luive been obtained from the brain 
and nerve tissue of animals, eggs and milk, as well as 
from yeast, and the seeds of juaize, peas, and wheat. 
The lecithins are described as white, wax-like substances. 



THE VOLATILE PART OF PLANTS. 123 

imperfectly crystallizable, similar to protagon in their 
deportment toward water, and readily decomposed into 
cholin, glyceropliosplioric acid, and one or more fatty 
acids. Three lecithins appear to have been identified, 
yielding resj^ectively, on decomposition, stearic, palmitic, 
and oleic acids. 

The formula C44H00NPO9 is that of distearic lecithin, 
which is composed of glyceryl, C3PI5, united to two 
stearic acid radicals, and also to phosphoric acid, which 
again is joined to cholin, as represented by the formula— 

/0C„H3,,0 
C3H,,— OCigH.-.O 

\0P0 /OC2H4N(CH3)30H 

Lecithin is believed to be a constant and essential in- 
gredient of plants and animals. 

Protagon, dooHsosNgPOgs, discovered by Liebreich in 
the brain of animals, has been further studied by Gam- 
gee & Blankenhorn. It is a white substance that swells 
up with water to a gelatinous mass and finally furms an 
opake solution. From solution in ether or alcohol it can 
be easily obtained in needle-shaped crystals, whose com- 
position is given below. Alkalies decompose protagon 
into glycero-phosphoric acid, stearic and other fatty 
acids, and cholin or neurin. Protagon was formerly 
confounded witli lecithin and thought to exist in plants^ 
but its presence in the latter has not been established. 

Protagon. Lecithin. 

CarTSon cn.39 05.43 

Hv<lrosen . 10.G9 11.16 

Nitrosen 2.39 1.73 

riiosphorus 1.07 3.84 

Oxygen 19.46 17.84 

100.00 100.00 

Knop was the first to show" that the crude fat which is 
extracted from plants by ether contains an admixture of 
some substance of which phosphorus is an ingredient. 
In the oil obtained from the sugar-pea he found 1.25 per 
cent, of phosphorus. Toplor afterwards examined the 



124 HOW CROPS GROW. 

oils of a large number of seeds for pliospliorus with the 
subjoined results : 



Hourcc of Per cent, of 

fat. phosphorus. 

Lupin 0.29 

Tea 1.17 

Horse-bean 0.72 

Vetch o.&O 

Winter lentil 0.39 

Horse-chestnut 0.40 

Chocolate-bean none 

Millet " 

Poppy " 



Sotirce of Per cent, of 

fat. phos2>lioras. 

Walnut trace 

Olive none 

Wlieat 0.25 

Barley ...0.28 

Rye 0.31 

Oat 0.-44 

Flax none 

Colza " 

Mustard " 



It is probable that the phosphorus in these oils existed 
in the seeds as lecithin, or as glycerophosphoric acid, 
Avliich is produced in the decomposition of lecithin. Max- 
well (Oonstitiition of the Legumes), reckoning from the 
phosphoric acid found in the ether-extract, estimates the 
pea kernel to contain 0.3G8 per cent, the horse-bean 
{FaM vulgaris) 0. GOO per cent, and the vetch 0.532 per 
cent of Iccitiun. Lecithin is thus calculated to make up 
19.63 per cent of the crude fat of the pea, 31.54 per 
cent of the crude fat of the horse-bean, and 35.24 per 
cent of that of the vetch. 

Chlorophyl, i. e. , leaf -green, is the name applied to 
the substance which occasions the green color in vegeta- 
tion. It is found in all those parts of most annual plants 
and of the annually renewed parts of, perennial plants 
which are exposed to light. The green parts of plants 
usually contain chlorophyl only near their surface, and 
in quantity not greater than one or two per cent of tlie 
fresh vegetable substance. 

Chlorophyl, being solulde in ether, accompanies fat or 
wax wlien these are removed from green vegetable mat= 
ters by this solvent. It is soluble in alcohol and hydro- 
chloric and sulphuric acids, imparting to these liquids an 
intense green color, but it suffers alteration and decom- 
position so readily that it is doubtful if the composition 
of chlorophyl, as it exists in the living leaf, is accurately 
known, especially since it is there mixed with other sub- 



THE VOLATILE PART OF PLAKTS. 135 

stances, separation from which is difficult or imprac- 
ticable. 

Chlorophyllan, obtained by Hoppe-Seyler from grass, 
separates from its solution in hot alcohol in characteristic 
acicular crystals which are brown to transmitted light, 
and in reflected light are blackish green, with a velvety, 
somewhat metallic lustre. This substance has the con- 
sistence of beeswax, adheres firmly to glass, and at about 
230° melts to a brilliant black liquid. Tlie crystallized 
chlorophyllan has a composition as follows : 

CHLOROPHYLLAN. 

Carbon 73.3G 

Hydrogen 9.72 

Nitrogen 5.C8 

Fliospliorus ". . 1.38 

Magnesium 0.34 

Oxygen 9.52 

100.00 

Chlorophyllan is cliemically distinct from chlorophyl, 
as proved by its optical properties, but in what the dif- 
ference consists is not understood. Boiling alkali decom- 
poses it with formation of chlorophyllanic acid that 
may be obtained in blue-black crystals, and at the same 
time glycerophosphoric acid and cholin, the decomposi- 
tion-products of lecithin, are produced. Tschirch found 
that chlorophyllan, by treatment with zinc oxide, yields 
a substance whose optical properties lead to the belief 
that it is identical with the chlorophyl that occurs in the 
living plant. It was obtained as a dark-green powder, 
but its exact chemical composition is not known. 

The special interest of chlorophyl lies in the fact that 
it is to all appearance directly concerned in those con- 
structive processes by which the plant composes starch 
and other carbhydrates out of the mineral substances 
w^hich form its food. 

Xanthophyl is the yellow coloring matter of leaves 
and of many flowers. It occurs, together with chlorophyl, 
in green leaves, and after disappearance of chlorophyl 
remains as the principal pigment of autumn foliage. 



120 HOW CHOPS GliOW« 



CHAPTER II. 
THE ASH OF PLANTS. 

§ 1- 
THE INGREDIENTS OF THE ASH. 

As lias been stated, the volatile or destructible part of 
plauts, i. e., the part wliicli is converted into gases or 
vapors under the ordinary conditions of burning, con- 
sists chiefly of Carbon, Hydrogen, Oxygen and Nitro- 
gen, together witii small quantities of Sulphur and Phos- 
phorus. These elements, and such of their compounds 
as are of general occurrence in agi'icultural plants, viz., 
the Organic Proximate Principles, have been already 
described in detail. 

The non-volatile part or ash of plants also contains, 
or may contain. Carbon, Oxygen, Sulphur, and Phos- 
phorus. It is, however, in general, chiefly made up of 
eight other elements, whose common compounds are 
permanent at the ordinary heat of burning. 

In the subjoined table, the names of the 12 elements 
of the ash of plants are given, and they are grouped 
under two heads, the non-metals and the metals, by rea- 
son of an important distinction in their chemical nature. 

ELEMENTS OF THE ASH OF PLANTS. 

Non-Metals. Metals. 

Oxygon. Potassium. 



Carbon. 


Sodiiun. 


Snlpliur. 


( 'ale i Tim. 


Phosi)liorus. 


Masjjnesium. 


Silicon. 


Iroii. 


Chlorine. 


Manganese. 



If to the above be added 

Hydrogen and Nitrogen 



THE ASiI OF PLANTS. 127 

the lisfc includes all the elementary substances that belong 
to agricultural vegetation. 

Hydrogen is never an ingredient of the perfectly 
burned and dry ash of any plant. 

Nitrogen may remain in the ash under certain con- 
ditions in the form of a Cymiide (compound of Carbon 
and Nitrogen), as will be noticed hereafter. 

Besides the above, certain otlier elements are found, either occasion- 
ally in coninion plants, or in some particular kind of vegetation ; these 
are Iodine, Bromine, Fluorine, Titanium, Boron, Arsenic, Lithium, 
Rubidium, Barium, Aluminum, Zinc, Cojjper. These elements, how- 
ever, so far as known, have no special importance in agricultural 
chemistry, and mostly require no further notice. 

We may now complete our study of the Composition 
of the Plant by attending to a description of those ele- 
ments that are peculiar to the ash, and of those com- 
pounds which may occur in it. 

It will be convenient also to describe in this section 
some substances, which, althougli not ingredients of the 
ash, may exist in the plant, or are otherwise important 
to be considered. 

The Non-metallic Elements, which we shall first 
notice, though differing more or less widely among them- 
selves, have one point of resemblance, viz., they and their 
compounds with e:ich other have acid properties, i. e., 
they either are acids in tlie ordinary sense of being sour 
to the taste, or enact the part of acids by uniting to met- 
als or metallic oxides to form salts. We may, therefore, 
designate them as the acid elements. They are Oxygen, 
Sulphur, Phosphorus, Carbon, .Silicon, and Chlorine. 

With the exception of Silicon, and the denser forms of 
Carbon, these elements by tliemselves are readily volatile. 
Their compounds with each other, whicli may occur in 
vegetation, are also volatile, with two exceptions, viz.. 
Silicic and Phosphoric acids. 

In order that they may resist the high temperature at 
which ashes are formed, they must be combined with the 
metallic elements or their oxides as salts. 



128 now CEOPS GROW. 

Oxygen, Symhol 0, atomic ivciglit 16, is an ingredient 
of the ash, since it unites with nearly all the other ele- 
ments of vegetation, either during the life of the plant, 
or in the act of combustion. It unites with Carbon, 
Sulphur, Phosphorus, and Silicon, forming acid bodies ; 
while with the metals it 2:)roduces oxides, which have the 
characters of bases. Chlorine alone of the elements of 
the plant does not unite with oxygen, either in the living 
plant, or during its combustion. 

CARBOI^ AND ITS COMPOUNDS. 

Carbon, Sym. C, at. wt. 12, has been noticed already 
with sufficient fullness (p. 14). It is often contained as 
charcoal in the ashes of the plant, owing to its being en- 
veloped in a coating of fused saline matters, which sliield 
it from the action of oxygen. 

Carbon Dioxide, commonly termed Carbonic acid, 
Sym. CO2, molecular tueiglit 44, is the colorless gas 
which causes the sparkling or effervescence of beer and 
soda water, and the frothing of yeast. 

It is formed by the oxidation of carbon, when vegeta- 
ble matter is burned (Exp. G). It is, therefore, found 
in the ash of plants, combined with those bases which in 
the living organism existed in union with organic acids ; 
the latter being destroyed by burning. 

It also occurs in combination with calcium in the tissues 
of many plants. Its compounds with bases are carhon- 
ates, to be noticed presently. When a carbonate, as mar- 
ble or limestone, is drenched with a strong acid, like 
vinegar or muriatic acid, the carbon dioxide is set free 
w^ith effervescence. 

Carbonic Acid, H2CO3, or C0(0II)2, mo. wt. G2. 
This, the carbonic acid of modern chemistry, is not known 
as a distinct substance, since, when set free from carbon- 
ates by the action of a stronger acid, it falls into carbon 
dioxide and water : 



THE ASH OF PLANTS. 129 

CaCOg + 2 HCl = CaClz + K2CO3 and H^COg = H,0 + COj. 

Carbon dioxide is also termed anhydrous carbonic acid, 
or again, carbonic anhydride. 

Cyanogen, .9 //;/i. C2^'2- — This important comiiound of Carbon and Ni- 
trogen is a gas wliicli lias an odor like that of peach-i)its, and which 
bvirns on contact with a lighted taper Avith a tine purple flame. In its 
union with oxygen by combustion, carbon dioxide is formed, and nitro- 
gen set free : 

C2N2 + 4 O = 2 CO2 + N,. 

Cyanogen may be prei^ared by heating an intimate mixture of two 
parts by weight of ferrocyanide of potassium (yellow prussiate of 
potash) and three parts of corrosive sublimate. The operation may 
be conducted in a test-tube or small flask, to the mouth of which is 
fitted a cork penetrated by a narrow glass tube. On applying heat, the 
gas issues, and may be set on fire to observe its beautiful flame. 

Cyanogen, combined with iron, forms the Prussian blue of com- 
merce, and its name, signifying the blue-producer, was given to it from 
that circumstance. 

Cyanogen unites with the metallic elements, giving rise to a series 
of bodies which are termed Cyanides. Some of these often occur in 
small quantity in the ashes of plants, being produced in the act of 
burning by the union of nitrogen with carbon and a metal. For this 
result, the temperature must be very high, carbon must be in excess, 
the metal is usually potassium or calcium, the nitrogen may be either 
free nitrogen of the atmosphere or that originally existing in the 
organic matter. 

With hydrogen, cyanogen forms the deadly poison hydrocyanic or 
prussic acid, HCy, which is produced from amygdalin, one of the ingre- 
dients of bitter almonds, peach, and cherry seeds, when these are 
crushed in contact with water. 

AVhen a cyanide is brought in contact with steam at high tempera- 
tures, it is decomposed, all its nitrogen being converted into ammonia. 

Cyanogen is a normal ingredient of one common plant. The oil of 
mustard is allylsnlphocyanate, CsH^CNS. 

SULPHUR AND ITS COMPOUNDS. 

Sulphur, Sym. S, at. tvt. 32. — The properties of tliis 
element have been already described (p. 25). Some of 
its compounds liave also been briefly alluded to, but re- 
quire more detailed notice. 

Hydrogen Sulphide, Sijm.. H^S, mo. wt. 34. This substance, familiarly 
known as sulphuretted hydrogen, occurs dissolved in the water of nu- 
merous so-called siilphur springs, as those of Avon and Sharon, N. Y., 
from which it escapes as a fetid gas. It is not unfrequently emitted 
from volcanoes and fumaroles. It is likewise produced in the decay of 
organic bodies wliich contain sulpliur, especially eggs, the intolerable 
odor of which, when rotten, is largely due to this gas. It is evolved 
from manure heai^s, from salt marshes, and even from the soil of moist 
meadows. 

9 



130 HOW CROPS GROW. 

The ashes of iilants sometimes yield this gas when they are moistcnecl 
with water. In snch cases, a sulphide of potasslani or calcium has l)een 
formed in small qnantity dnring the incineration. 

Hydrogen Sulphide is set free in the gaseous form by the action of an 
acid on various sulphides, as those of iron (Exp. 17), antimony, etc., as 
well as by the action of water on the .'julphides of the alkali and alkali- 
earth metals. It may be also generated by passing hydrogen gas into 
melted svilphur. 

Sulphuretted hydrogen has a slight acid taste. It is highly poisonous 
and destructive, both to animals and plants. 

SuLPHUK Dioxide, commonly called Sulphurous Acid, Sijni. SO,, mo. 
ivb. G-1. When sulphur is burned in the air, or in oxygen gas, it forins 
copious white suffocating fumes, which consist of one atom of sulphur, 
united to two atoms of oxygen ; SO2 (Exp. 15). 

Sulpliur dioxide is characterized by its power of discharging, for a 
time at least, most of the red and blue vegetable colors. It has, how- 
ever, no action on many yellow colors. Straw and wool are bleached 
by it in the arts. 

Sulphur dioxide is emitted from volcanoes, and from fissures in the 
soil of volcanic regions. It is produced when bodies containing sul- 
l)hur are burned with imperfect access of air, and is thrown into the 
atmospliere in large (luantities from fires which are fed by mineral 
coal, as well as from the numerous roasting heaps of certain metallic 
ores (sulphides) which are wrought in mining regions. 

Sulphur dioxide may unite with bases, yielding salts known as sul- 
2'>hites, some of which, viz., calcium sulphite and sodium sulphite, are 
employed to check or prevent fermentation, an effect also produced by 
the acid itself. 

Sulphur-Trioxide, Sym. SO3, mo. lot. 80, is known 
to the chemist as a white, silky solid, which attracts 
moisture wit!) great avidity, and, when thrown into 
water, hisses like a hot iron, forming sulphuric acid. 
Sulphur trioxidc was formerly termed sulphuric acid or 
anhydrous sulphuric acid, aud now it is common in 
statements of analysis to follow this usage. 

Sulphuric Acid, Stjm. 110804, ^o. wt. 98, is a sub- 
stance of the highest importance, its manufacture being 
the basis of the chemical arts. In its concentrated form 
it is known as oil of vitriol, and is a colorless, heavy 
liquid, of an oily consistency, and sharp, sour taste. 

It is manufactured on the large scale by mingling sul- 
phur dioxide gas, nitric acid gas, and steam, in large 
lead-lined chambers, the floors of which are covered with 
water. The sulphur dioxide takes up oxygen from the 



THE ASH OF PLANTS. 131 

nitric acid, and the sulphuric acid tlins formed dissolves 
in tlie water, and is afterwards boiled down to the proper 
strength in glass vessels. 

The chief agricultural ap])licati()n of sulphuric acid is 
in the preparation of '' su})erphosphate of lime," which 
is consumed as a fertilizer in immense quantities. This 
is made by mixing togetlier sulphuric acid, somewhat 
diluted with water, with bone-dust, bone-ash, or some 
mineral phosphate. Commercial oil of vitriol is a mix- 
ture of sulphuric acid with more or less water. The 
strongest oil of vitriol commonly made, or "0G° acid," 
contains 93.5% of H2SO4. The so-called ^'60° acid" 
contains 77.6% II0SO4 or 83% of 00° acid. Chamber 
acid or "51° acid" contains 03.6% H2SO4, or 07% of 
06° acid. 

Sulphuric acid occurs in the free state, though ex- 
tremely dilute, in certain natural waters, as in the Oak 
Orchard Acid Spring of Orleans, N. Y., where it is pro- 
duced by the oxidation of sulphide of iron. 

Sulphuric acid is very corrosive and destructive to most 
veoetable and animal matters. 

o 

Exp. C3.— Stir a little oil of vitriol with a pine stick. The wood is im- 
mediately browned or blaokened, and a portion of it dissolves in tlie 
acid, communicating a dark color to the latter. Tlie commercial acid 
is often brown from contact with straws and chips. 

Strong sulphuric acid produces great heat when mixed with water, 
as is done for making superpliosphate. 

Exp. 54.— Place in a thin glass vessel, as a beaker glass, 30 c. c. of water ; 
into this pour in a fine stream 120 grams of oil of vitriol, stirring all the 
while with a narrow test-tube, containing a teaspoonf ul of water. If the 
acid be of full strength, so much heat is thus generated as to boil the 
water In the stirring tube. 

In mixing oil of vitriol and water, the acid should always be slowly 
poured into the water, with stirring, as above directed. Wlien water 
is added to the acid, it floats upon the latter, or mixes with it but super- 
ficially, and the liquids may be thrown about by the sudden formation 
of steam at the points of contact, when subsequently stirred. 

Sulphuric acid forms with tlie bases an important class 
of salts — the sulphates, to be presently noticed — some of 
which exist in the ash, as well as in the sap of plants. 



132 HOW CROPS GROW. 

When organic matters containing sulphur — as hair, 
albumin, etc. — are burned with full access of air, this 
element remains in the ash as sulphates, or is partially 
dissipated as sulphur dioxide. 

IHOSPHORUS AKD ITS COMPOUNDS. 

Phosphorus, St/m. P, at. ivt. 31, has been sufficiently 
described (p. ;i7). Of its numerous compounds but two 
require additional notice. 

Phosphorus Pentoxide, Sijm, PoOg, mo, tut. 142, 
does not occur as such in nature. When phosphorus is 
burned in dry air or oxygen, anhydrous phosphoric acid 
is tlie snow-like product (Exp. 18). The term '^^phos- 
phoric acid," as now encountered in fertilizer analyses, 
has reference to "anhydrous phosphoric acid," as phos- 
phorus pentoxide was formerly designated. Phosphorus 
pentoxide has no sensible acid properties until it has 
united to water, which it combines with so energetically 
as to produce a hissing noise from the heat developed. 
On boiling it with water for some time, it comj^letely dis- 
solves, and the solution contains — 

Phosphoric Acid, Sym. H3PO4, 98. — The chief in- 
terest which this compound has for the agriculturist lies 
in the fact that the combinations wdiich are formed be- 
tween it and various bases — phosjjhatcs — are among the 
most important ingredients of plants and their ashes. 

When organic bodies containing phosphorus, as le- 
cithin (p. 122), and, perhaps, some of the albuminoids, 
are decomposed by heat or decay, the phosphorus appears 
in the ashes or residue, in the condition of phosphoric 
acid or phosphates. 

The formation of several phosphates has been shown in 
Exp. 20. Further account of them will be given under 
the metals. 

CHLORINE AND ITS COMPOUNDS. 

Chlorine, Sym. CL, at. lot. 35.5. — This element exists 



THE ASH OF PLANTS. 133 

in the free state as a greenish-yellow, suffocating gas, 
which has a peculiar odor, and the property of bleaching 
vegetable colors. It is endowed with the most vigorous 
affinities for many other elements, and hence is never met 
with, naturally, in the free state. 

Exp. 55.— Chlorine may be j)i-epared by beating a mixtnre of bydio- 
cbloric acid and black oxide of manganese or red-lead. The gas being 
nearly five tinxes as heavy as common air, may be collected in glass 
bottles by passing the tube which delivers it to the bottonx of the re- 
ceiving vessel. Care nuist be taken not to inhale it, as it energetically 
attacks the interior of the breathing passages, i^roducing the disagree- 
able symptoms of a cold. 

Chlorine dissolves in water, forming a yellow solution. 

In some form of combination chlorine is distributed 
over the whole earth, and is never absent from the plant. 

The compounds of chlorine are termed chlorides, and 
may be prepared, in most cases, by simply putting their 
elements in contact, at ordinary or slightly elevated tem- 
peratures. 

Hydrochloric Acid, Sym. HCl, mo. xvt. 36.5.— When Chlorine and 
Hydrogen gases are mingled together, they slowly combine if exposed 
to diffused light ; but if placed in the sunshine, they unite exi^losively, 
and hydrogen chloride or hydroclihjric acid is formed. This compound 
is a gas that dissolves with great avidity in water, forming a liquid 
wliich has a sharp, sour taste, and jjossesses all the characters of an 
acid. 

The niuriatic acid of the apothecary is water holding in solution 
several hundred times its bulk of hydrochloric acid gas, and is pre- 
pared from common salt, whence its ancient name, spirits of salt. 

Hydrochloric acid is the usual source of chlorine gas. The latter is 
evolved from a heated mixture of this acid with black oxide of manga- 
nese. In this reaction hydrogen of the hydrochloric acid unites 
with oxygen of the oxide of manganese, producing water, while 
chloride of manganese and free chlorine are separated. 
4 HCl + MnOg = MnCla + 2 H, O + 2 CI. 

When chlorine, dissolved in water, is exposed to the sunlight, there 
ensues a change the reverse of that just noticed. Water is decom- 
posed, its oxygen is set free, and hydi-ochloric acid is formed. 
HjO + 2 Cl= 2 HCl + O. 

The two reactions iust noticed are instructive examples of the differ- 
ent play of affinities between several elements under unlike circum- 
stances. 

This acid is a ready means of converting various metals or metallic 
oxides into chlorides, and its solution in water is a valuable solvent 
and reagent for the purpose of the chemist. 



134 HOW CROPS GROW. 

Iodine, ,*?7/m. T, at. wt. 127.— This intorostiiig body is a black solid at 
ordinary temperatures, having an odor resembling that ol' chlorine. 
Gently heated, it is converted into a violet vapor. It occurs in sea- 
weeds, and is obtained from their ashes. It gives with starch a blue or 
purple compound, and is hence emijloyed as a test for that substance 
(p 49). It is analogous to chlorine in its chemical relations. It is not 
known to occur in sensible quantity in agricultural plants, although it 
may well exist in the grasses of salt-bogs, and in the produce of soils 
which arc manured with sea-weed. 

Bromine and Fluorine may also exist in very small quantity in 
plants, but these elements require no further notice in this treatise. 

SILICON AN^D ITS COMPOUNDS. 

Silicon, Sym. Si, at. lut. 28. — This element, in the 
free state, is only known to the chemist. It may be pre- 
pared in three modifications : one, a brown, powdery 
substance ; another, resembling plumbago, and a third, 
that occurs in crystals, having the form and nearly the 
hardness of the diamond. 

Silicon Dioxide, Sym. SiO.^, mo. tut. fiO. — This com- 
pound, known also as Silica, is widely diffused in nature, 
and occurs to an enormous extent in rocks and soils, both 
in the free state and in combination with other bodies. 

Free silica exists in nearly all soils, and in many rocks, 
especially in sandstones and granites, in the form known 
to mineralogists as qitartz. The glassy, white, or trans- 
parent, often yellowish or red, fragments of common sand, 
icliich arc hard enough to scratch glass, are almost inva- 
riably this mineral. In the purest state, it is rock-crys- 
tal. Jasper, flint, and agate are somewhat less pure 
silica. 

Silicates. — Silica is extremely insoluble in pure water 
and in most acids. It has, therefore, none of the sensi- 
ble qualities of acids, but is nevertheless capable of union 
with bases. It is slowly dissolved by strong, and espe- 
cially by hot, solutions of potash and soda, forming sol- 
uble silicates of the alkali metals. 

Exp. 56.— Formation of potassium silicate. Heat a piece of quartz or 
flint, as large as a chestnut, as hot as possible in the fire, and quench 
siiddenly in cold water. Reduce it to flue powder in a porcelain mor- 
tar, and boil it in a porcelain disli with twice its weight of caustic p'>-' 



THE ASH OF PLANTS. 135 

asli, and eight or ten times as much water, for two liours, taking care 
to supijly the water as it evaporates. Pour off tlie wliole into a tall 
narrow bottle, and leave at rest until the undissolved silica has settled. 
The clear liquid is a basic potassium silicate, i. e., a silicate which coii_ 
tains a number of mole(;ules of base for each molecule of silica. It 
has, in fact, the taste and feel of potasli solution. The so-called tvater- 
glass, now employed in the arts, is a similar sodium silicate. 

When silica is strongly heated with potash or soda, or 
with lime, magnesia, or oxide of iron, it readily melts to- 
gether and nnites with these bodies, though nearly infus- 
ible by itself, and silicates are the result. The silicates 
thus formed with potash and soda are soluble in water, 
like the product of Exp. 56, when the alkali exceeds a 
certain proportion — when highly basic ; but, with silica 
in excess (acid silicates), they dissolve with difficulty. 
A mixed silicate of sodium, calcium, and aluminum, with 
a large proportion of silica, is nearly or altogether insol- 
uble, not only in water, but in most acids — constitutes, 
in fact, ordinary glass. 

A multitude of silicates exist in nature as rocks and 
minerals. Ordinary clay, common slate, soapstone, mica, 
or mineral isinglass, feldspar, hornblende, garnet, and 
other compounds of frequent and abundant occurrence, 
are silicates. The natural silicates may be roughly dis- 
tinguished as belonging to two classes, viz., the acid sil- 
icates (containing a preponderance of silica) and lasic 
silicates (with large proportion of base). The former are 
but slowly dissolved or decomposed by acids, while tlic 
latter are readily attacked, even by carbon dioxide acid. 
Many native silicates are anhydrous, or destitute of 
water ; othsrs are hydrous, i. e., they contain water as a 
large and essential ingredient. 

The Silicic Acids. — Various silicic acids — compounds 
of sihca with water — are known to the chemist, or are 
represented by the silicates found in nature. The silicic 
acids themselves have little stability and are readily re- 
solved into water and silica . 

Soluble Silica^ Si(OII).^? — This body in known only in 



13G HOW CROPS GROW. 

solution. It is formed when the solution of an alkali- 
silicate is decomposed by means of a large excess of some 
strojig acid, like the hydrochloric or sulphuric. 

Exp. 57. — DiUite half tlie solution of potassium silicate obtained in 
Exp. 56 with ten times its volume of water, and add diluted hydrochloric 
acid gradually until the liquid tastes sour. In this Exp. the hydrochlo- 
ric acid decomj)oses and destroys the potassium silicate, uniting itself 
to the base with production of chloride of potassium, which dis- 
solves in the water present. The silioa thus liberated unites chemi- 
cally with water, and remains also in solution. 

By appropriate methods Doveri and Graham have 
obtained solutions of silica in pure water. Graham pre- 
pared a liquid that gave, when evaporated and heated, 
14 per cent of anhydrous silica. This solution was clear, 
colorless, and not viscid. It reddened litmus-paj^er like 
an acid. Though not sour to the taste, it produced a 
peculiar feeling on the tongue. Evaporated to dryness at 
a low temperature, it left a transparent, glassy mass, 
which had the composition HaSiO^. This dry residue 
was insoluble in water. These solutions of silica in pure 
water are incapable of existing for a long time without 
suffering a remarkable change. Even when ]irotected 
as much as possible from all external agencies, they 
sooner or later, usually in a few days or weeks, lose their 
fluidity and transparency, and coagulate to a stiff jelly, 
from the separation of a nearly insoluble hydrate of silica, 
which we shall designate as gelatinous silica. 

The addition of yoooo ^^ ^^ alkali or earthy carbon- 
ate, or of a few bubbles of carbon dioxide gas to the strong 
solutions, occasions their immediate gelatinization. A 
minute quantity of potash or soda, or excess of hydro- 
chloric acid, prevents their coagulation. 

Gelatinous Silica. — This su])stance, which results 
from the coagulation of the soluble silica just described, 
usually appears also when the strong solution of a silicate 
has strong hydrochloric acid added to it, or when a sili- 
cate is decomposed by direct treatment with a concen- 
trated acid. 



THE ASn OF PLANTS. 137 

It is a v/hite, opaline, or transparent jelly, whicli, on 
drying in the air, becomes a fine, white powder, or forms 
transparent grains. This powder, if dried at ordinary 
temperatures, has a composition nearly corresponding to 
the formula HiSisOg, or to a compound of 3 SiOo with 
2 H.O. At the temperature of 212° F., it loses half its 
watei". At a red heat it becomes anhydrous. 

Gelatinous silica is distinctly, though very slightly, 
soluble in water. Fuchs and Bresser have found by ex- 
periment that 100,000 parts of water dissolve 13 to 14 
parts of gelatinous silica. 

The hydrates of silica which have been subjected to a 
heat of 212°, or more, appear to be totally insoluble in 
pure water. 

These hydrates of silica are readily soluble in solutions 
of the alkalies and alkali carbonates, and readily unite 
with moist, slaked lime, forming silicates. 

Exp. 58.— Gelatinous Silica.— Foixr a smaU i^ortion of the solution of 
sUicate potassium of Exp. 50 into strong hydrochloric acid. Gelatinous 
silica separates and falls to the hottom, or the whole liquid becomes a 
transparent jelly. 

Exp. 59. — Conversion of soluble into insoluble hi/dnitcd silica. — Evapo- 
rate the solution of silica of Exp. 57, which contains free hydrochloric 
acid, in a porcelain dish. As it becomes concentrated, it is very likely 
to gelatinize, as happened in Exp. 58, on accouiit of the removal of the 
solvent. Evaporate to perfect dryness, finally on a water-bath (i. e., on 
a vessel of boiling water which is covered by the dish containing the 
solution). Add to the residue water, which dissolves away the chlo- 
ride of potassium, and leaves Insoluble hydrated silica, 3 Si02 H2O, as 
a gritty powder. 

In the ash of plants, silica is usually found in com- 
bination with alkali-metals or calcium, owing to the 
high temperature to which it has been subjected. 

In the i)lant, however, it exists chiefly, if not entirely, 
in the free state. 

TiTA^firM, an element wliich has many analogies with silicon, though 
rarely occurring in large quantities, is yet often present in the forni 
of Titanic ari(l,TiO.,, in rocks and soils, and, according to Salm-IIorst- 
niar, may exist in the ashes of barley and oats. 

Arsenic, in minute quantity, was found V)y Davy in turnips whicli 
had been nuinured witli a fertilizer (superphosphate), in whose prep- 
aration arsenical oil of vitriol was employed. 



138 HOW CROPS GROW. 

When arsenic, in the form of Paris green or London purple, is applied 
to land the arsenic soon becomes converted into highly insoluble iron 
compounds and is not taken up by plants in appreciable quantity. 

The Metallic Elements which remain to be noticed, 
viz.: Potassium, Sodium, Calcium, Magnesium, Iron, 
Manganese, Aluminium, Zinc, and Copper, are basic in 
their character, i. e., they unite with the acid bodies 
that have just been described, to jiroduce salts. Each 
one is, in this sense, the base of a series of saline com- 
pounds. 

Alkali-metals. — The elements Potassium and Sodium 
are termed alhali-meials. Their oxides dissolve in and 
chemically unite to water, forming hydroxides that are 
called alkalies. The metals themselves do not occur in 
nature, and can only be prepared by tedious chemical 
processes. They are silvery-white bodies, and are lighter 
than water. Exposed to the air, they quickly tarnish 
from the absorption of oxygen and moisture, and are 
rai)idly converted into the cori-esponding alkalies. 
Thrown upon water, they mostly inflame and burn with 
great violence, decoin2:)osing the liquid. Exp. 11. 

Of the alkali-metals, Potassium is invariably found in 
all plants. Sodium is especially abundant in marine and 
strand vegetation ; it is generally found in agricultural 
l)lants, but is sometimes present in them in but small 
quantity. 

POTASSIUM a:n"d its compounds. 

Potassium, Sym. K ; * at. wt. 30. — When heated in 
the air, this metal burns with a beautiful violet light, 
and forms potassium oxide. 

Potassium Oxide, or Potash, K2O, 94, is the so- 
called '^actual potash " tliat figures in the analyses of 
l^lants and valuation of fertilizers. It is, however, scarcely 
known as a substance, because it energetically unites 
with water and forms hydroxide. 

* From the Latin name Kallum. 



THE A3U 01*' PLAINTS. loO 

Potassium Hydroxide, KOH, 5G, is tlic caustic 
potasJi of tiie cipotlieciiry and chemist. It may be pro- 
cured iu white, opaque masses or sticks, which rapidly 
absorb moisture and carbonic acid from tlie air, and 
readily dissolve in water, iormhig potash-lye. It strongly 
corrodes many vegetable and most animal matters, and 
dissolves fats, forming potash-soaps. Both the oxide 
and hydroxide of potassium unite to acids forming salts. 

SODIUM AND ITS COMPOUNDS. 

Sodium, Na,* 23. — Burns with a brilliant, orange- 
yellow flame, yielding sodium oxide. 

Sodium Oxide, or Soda, NagO, 62, is practically lit- 
tle known, though constantly referred to as the base of 
the sodium salts. It unites to water, producing the hy- 
droxide. 

Sodium Hydroxide, or Caustic Soda, NaOII, 40. — 
This body is like caustic potash in appearance and gen- 
eral characters. It forms soaps with the various fats. 
While the potash-soaps are usually soft, those made with 
soda are commonly hard. 

Alkali-earth Metals. — The two metallic elements 
next to be noticed, viz., Calcium and Magnesium, give, 
with oxygen, the alhali-earths, lime and magnesia. The 
metals are only procurable by difficult chemical pro- 
cesses, and from their eminent oxidability are not found 
in nature. They are but a little heavier than water. 
Their oxides are but slightly soluble in water. 

calcium AND ITS COMPOUNDS. 

Calcium, Ca, 49, is a brilliant ductile metal having a 
light yellow color. In moist air it rapidly tarnishes and 
acquires a coating of lime. 

Calcium Oxide, or Lime, CaO, 5G, is the result 



* From the Latin name Natrlavi. 



140 now CKors guow. 

of the oxidation of calcium. It is prepared for nso 
in tlie arts by subjecting limestone or oyster-shells to an 
intense lieat, and usually retains the form and much of 
the h[irdness of the material from which it is made. It 
has the bitter taste and corroding properties of the alka- 
lies, though in a less degree. It is often called quich 
lime, to distinguish it from its compound with water. 
It may occur in the ashes of plants when they have been 
maintained at a high heat after the volatile matter iia»3 
been burned away. 

Calcium Hydroxide, Oa (0H)2, 74. — Quick-lime, 
when exposed to the air, gradually absorbs water and 
falls to a fine powder. It is then said to be air-slacked. 
When water is poured upon quick-lime it penetrates the 
pores of the latter, and shortly the falling to powder of 
the lime and the development of mucii heat give evi- 
dence of chemical union between the lime and the water. 
This chemical combination is further proved by the in- 
crease of weight of the lime, 56 lbs. of quick-lime becom- 
\ng 74 lbs. by loater-sla'^hing. On heating slacked lime 
to redness, water is expelled, and calcium oxide remains. 

When lime is agitated for some time with much water, 
and the mixture is allowed to settle, the clear liquid is 
found to contain a small amount of lime in solution (one 
part of lime to 700 parts of water). This liquid is called 
■lime-water,. ?irL<l has already been noticed as a test for 
carbonic acid. Lime-water has the alkaline taste in a 
marked degree. 

MAGI^ESIUM A:N"D ITS COMPOUl^DS. 

Magnesium, Mg, 24. — Metallic magnesium has a sil- 
ver-white color. When heated in the air it burns with 
extreme brilliancy (magnesium light), and is converted 
into magnesia. 

Magnesium Oxide, or Magnesia, MgO, 40, is found 
in the drug-stores in the shape of a bulky white powder, 



THE ASII OF PLANTS. 141 

under the name of calcined magyiesia. It is prepared by 
subjecting either magnesium hydroxide, carbonate, or 
nitrate, to a strong heat. It occurs in the ashes of 
].)lants. 

Magnesium Hydroxide, Mg(0II)2, is produced 
slowly and without heat, when magnesia is mixed with 
water. It occurs rarely as a transparent, glassy mineral 
(Brucite) at Texas, Pa., Hoboken, N. J., and a few 
other places. It readily absorbs carbon dioxide and passes 
into carbonate of magnesium. Magnesium hydroxide is 
so slightly soluble in water as to be tasteless. It requires 
55,000 times its weight of water for solution (Fresenius). 

Heavy Metals. — The two metals remaining to notice 
are Iron and Manganese. These again considerably re- 
semble each other, though they differ exceedingly from 
the metals of the alkalies and alkali-earths. They are 
about eight times heavier than water. Each of these 
metals forms two basic oxides, which are commonly 
insoluble in pure water. 

mOK AND ITS COMPOUNDS. 

Iron, Fe,* 56. — The properties of metallic iron are so 
well known that we need not occupy any space in reca- 
l)itiilating them. 

Ferrous Oxide, or Protoxide of Iron, FeO, 72. — 
Wlien sul[)huric acid in a diluted state is put in contact 
with metallic iron, hydrogen gas shortly begins to escape 
in bul)l)les from the litjuid, and the iron dissolves, unit- 
ing with the acid to form ferrous sul])hate, the salt 
known commonly as copperas or green-vitriol. 

H2SO4, + Fe = FeSOi + H2. 

If, now, lime-water or potash-lye be added to the solu- 
tion of iron thus obtained, a white or greenish white pre- 
cipitate separates, which is ferrous hydroxide, Fe(OH)''^. 

*Froiii the Latin naiuu Fcrrmii. 



112 now CHOPS GROW. 

This })rccipitato r;i])idly absorbs oxygen from the air^ be* 
coming black and !]na]ly brown. The anhvdrous pro- 
toxide of iron is black. Carbonate of protoxide of iron 
is of frequent occurrence as a mineral (spathic iron), and 
exists dissolved in many mineral waters, especially in 
the so-called chalybeates. The ferrous salts are mostly 
white or green. 

Ferric Oxide, or Peroxide of Iron, FcoOg, IGO. — 
When ferrous hydroxide is exposed to the air, it acquires 
a brown color from union with more oxygen, and becomes 
ferric hydroxide Fe(0H)3. The yellow or brown rust 
which forms on surfaces of metallic iron when exposed to 
moist air is the same body. Ferric oxide is found in 
the ashes of all agricultural plants, the other oxides of 
iron passing into this when exposed to air at high tem- 
peratures. It is found in immense beds in the earth, 
and is an important ore (specular iron, haematite). It 
dissolves in acids, forming the ferric salts, which have 
a yellow color. 

Magnetic Oxide of Ikon, FegOi, or FeO.FooOa, is a combination 
of tlie two oxides above mentioned. It is blaclc, and is stroiiyly at- 
ti'acted by tlie magnet. It eonstitntes, in faet, tlie native magnet, or 
loadstone, and is a valnable ore of iron. 

Mais^ganese and its Compounds. 

Manganese, Mn, 55. — Metallic manganese is dillicult 
to procure in the free state, and much resembles ii'on. 
Its uxities are autilogous to those of iron Just noticed. 

Manganous Oxide, or Protoxide of Manganese, 
MnO, 71, has an olive-green color. It is tlie base of all 
the usually occurring salts of manganese. Its hydrox- 
ide, prepared by decomposing manganous sulphate by 
lime-water, is a white substance, which, on exposure to 
tlie air, shortly becomes brown and finally black from 
absorption of oxygen. The manganous salts are mostly 
pale rose-red in color. 
Manganic Oxide, Mn^Oa, oecurs native ay tiic mineral brautiitc, or, 



TITE ASn OF TLATs^TS, 143 

ponibiiiod with water, .is mnnganitr. It Is a siibstanoo having a rod or 
black-brown color. It dissolves in cold acids, forming salts of fin in- 
tensely red colcr. Tliese are, however, easily deconii)osetl by heat, or 
by organic bodies, into oxygen and nianganous salts. 

Red Oxide ok Manganese, Mn304, or MnO . MnoOg.— This oxide re>- 
niains when manganese or any of its other oxides are subjected to a 
liigh temperature with access of air. The metal and the protoxide 
gain oxygen by this treatment, the higher oxides lose oxygeu uiitii 
this compound oxide is formed, which, as its symbol shows, corres- 
pcnids to the magnetic oxide of iron. It is found in the ashes of plants. 

Black Oxide of Manganese, MnO,.— This body is found extensively 
in nature. It is employed in the preparation of oxygen and chlcriAe 
(bleaching powder), and is an article of commerce. 

Some other metals occur as oxides or salts in ashes, though not in 
such quantity or in such plants as to possess any agricultural sign ili- 
cance in this respect. 

Alumina, AUO,, the oxide of the metal Aluminium, is found in 
considerable quantity (20 to 50 per cent) in the ashes of the groTind pine 
{LycopoOlmn). It is united with an organic acid {t(trtaric, accor<ling to 
Bcrzelius ; malic, according to Ritthausen) in the plant itself. It is 
often found in small quantity in the ashes of agricultural plants, but 
v/hether an ingredient of the plant or due to x>articles of adhering clay 
is not in all cases clear. 

Zinc lias been found in a variety of yellow violet that grows about 
tlie zinc mines of Aix-la-Chapelle. 

CoprEii is frequently present in minute quantity in the ash of plants, 
especially of such as grow in the vicinity of manufacturing estal)lish- 
ments, where diUite solutions containing copper are thrown to waste. 

The Salts or Compounds of Metals with Non- 
metals found ill the iislies of plants or in the iinburncd 
plant remain to be considered. 

Of the elements, acids and oxides, that have been 
noticed as constituting the ash of plants, it must be re- 
marked that with the exception of silica, magnesia, oxide 
of iron, and oxide of manganese, they all exist in the 
ash in the form of salts (com]30unds of acids and bases). 
In the living agricultural plant it is probable that, of 
them all, only silica occurs in the uncombined state. 

We shall notice in the first place the salts which may 
occur in the ash of plants, and shall consider them under 
the following heads, viz. : Carbonates, Sulphates, Phos- 
phates, and Chlorides. As to the Silicates, it is unnec- 
essary to add anything hero to what has been already 
mentioned. 



144 11^ W CROPS C.KOW. 

The Caebonates which occur in the ashes of plants 
are those of Potassium, Sodium, and Calcium. The 
Carbonates of Magnesium, Iron, and Manganese are de- 
composed by the heat at which ashes are prepared. 

Potassium Carbonate, or Carbonate of Potash, 
KoCOo, 114. — The jjearl-asli of commerce is a tolerably 
pure form of this salt. When wood is burned, the potash 
which it contains is found in the ash, chiefly as carbon- 
ate. If wood-ashes are repeatedly washed or leached with 
Avater, all the salts soluble in this licpiid are removed ; by 
boiling this solution down to dryness, which is done in 
large iron pots, ci'ude potash is obtained, as a dark or 
brown mass. This, when somewhat purified, yields 
poarl-nsh. Potassium c;irbonatc, when pure, is white, and 
has a bitter, biting taste — the so-called alkaline taste. It 
has such attraction for water, that, when exposed to the 
air, it al)sorbs moisture and becomes a liquid. 

If hydrochloric acid be poured upon this carlionate a 
brisk effervescence immediately takes place, owing to the 
escape of carbon dioxide gas, and potassium chloride and 
water are formed, which remain behind. 

K2CO3 + 2 HCl = 2 KCl + K2O + COo. 

Potassium Bicarbonate, KHCO3. — A solution of 
potassium carbonate, when exposed to carbon dioxide, ab- 
sorbs the latter, and the potassium bicarbonate is pro- 
duced, so called because to a given amount of potassium 
it contains twice as much carbonic acid as the carbonate. 
Potash-salceratus consists essentially of this salt. It 
probahly exists in the juices of various plants. 

Sodium Carbonate, or Carbonate of Soda, 
NagOOs, lOG. — This substance, so important in the arts, 
was formerly made from the ashes of certain marine 
plants (Salsola and Salicornia), in a manner similar to 
that now employed in wooded countries for the prepara- 
tion of potash. It is at present almost wholly obtained 



THE ASn OF PLAN'TS. 145 

from common salt by somewhat complicated processes. 
It occurs in commerce in an impure state under the name 
of Soda-ash. United to water, it forms sal-soda, which 
usually exists in transparent crystals or crystallized 
masses. These contain 03 per cent of w\ater, which 
partly escapes when the salt is exposed to the air^ leav- 
ing a white, opaque powder. 

Sodium carbonate has a nauseous alkaline taste, not 
nearly so decided, however, as that of the carbonate of 
potassium. It is often present in the ashes of plants. 

Sodium Bicarbonate, NaHCOg. — The supercarbon- 
ate of soda of the apothecary is this salt in a nearly pure 
state. The cooking-soda of commerce is a mixture of 
this with some simi)le carbonate. It is prepared in the 
same way as potassium bicarbonate. The bicarbonate?, 
both of potassium and sodium, give off half their carbonic 
acid at a moderate heat, and lose all of this ingredient 
by contact with excess of any acid. Their use in baking 
depends upon these facts. They neutralize any acid 
(lactic or acetic) that is formed during the " rising " of 
the dough, and assist to make the bread " light" by in- 
flating it with carbon dioxide. 

Calcium Carbonate, or Carbonate of Lime, 
CaCOg, 112. — This compound is the white powder formed 
by the contact of carbon dioxide with lime-water. When 
slacked lime is exposed to the air, the water it contains 
is gradually displaced by carbon dioxide, and carbonate of 
lime is the result. Air-slacked lime always contains 
much carbonate. This salt is distinguished from lime 
by its being destitute of any alkaline taste. 

In nature carbonate of lime exists to an immense ex- 
tent as coral, chalk, marble, and limestone. These 
rocks, when strongly heated, especially in a current of 
air, part with carbon dioxide, and quick-lime remains 
behind. 

Calcium carbonate occurs largely in the ashes of most 
10 



146 now CEOPS GROW. 

plants, particularly of trees. In the manufacture ot 
potash it remains undissolved, and constitutes a chief 
part of the residual leached ashes. 

The calcium carbonate found in the ashes of plants is 
supposed to come mainly from the decomposition by heat 
of organic calcium salts (oxalate, tartrate, malate, etc.), 
which exist in the juices of the vegetable, or are abun- 
dantly deposited in its tissues in the solid form. Car- 
bonate of lime itself is, however, not an unusual compo- 
nent of vegetation, being found in the form of minute, 
rhombic crystals, in the cells of a multitude of plants. 

The Sulphates which we shall notice at length are 
those of Potassium, Sodium, and Calcium. Sulphate of 
Magnesium is well known as Epsom salts, and Sulphate 
of Iron is copperas or green vitriol. 

Potassium Sulphate, or Sulphate of Potash, 
K2SO4, 174. — This salt may be procured by dissolving 
potash or carbonate of potash in diluted sulphuric acid. 
On evaporating its solution, it is obtained in the form of 
hard, brilliant crystals, or as a white povv^der. It has a 
bitter taste. Ordinary potash, or pearl-ash, contains 
several per cent of this salt. 

Sodium Sulphate, or Sulphate of Soda, Na2S04, 
142. — Glauher^s salt is the common name of this famil- 
iar substance. It has a bitter taste, and is much em- 
ployed as a purgative for cattle and horses. It exists, 
either crystallized and transparent, containing 10 mole- 
cules, or nearly 5G ]:)cr cent of water, or anhydrous. 
The crystals rapidly lose their water when exposed to the 
air, and yield the anhydrous salt as a white powder. 

Calcium Sulphate, or Sulphate of Lime, CaS04, 
136. — The burned Plaster of Paris of commerce is this 
salt in a more or less pure state. It is readily formed by 
pouring diluted sulphuric acid on lime or marble. It is 
found in the ash of most plants, especially in that of 
clover, the bean, and other legumes. 



THE A8TI OF rLAN"TS. 147 

In nature, sulphate of lime is nsiially combined with 
two molecules of water, and tlius constitutes Gyj^sum, 
0aSO4 . 2 H2O, which is a rock of frequent and exten- 
sive occurrence. In the cells of many plants, as for 
instance the bean, gypsum may be discovered by the 
microscope in the shape of minute crystals. It requires 
400 times its weight of water to dissolve it, and being 
almost universally distributed in the soil, is rarely absent 
from the water of wells and springs. 

Land plaster is ground gypsum, that from Nova 
Scotia being white, that from Onondaga and other local- 
ities in New York KState gray in color. 

The PnospiiATES wdiich require special description 
are those of Potassium, Sodium, and Calcium. 

Numerous phosphates of each of these bases exist, or 
may be prepared artiilcially. But throe classes of phos- 
phates have any immediate interest to the agriculturist. 
As has been stated (p 132), phosphoric acid, prepared by 
boiling phos2)horus pentoxide with water, is represented 
by the symbol II3PO4. The phosphates may bo regarded 
as phosphoric acid in which one, two, or all the atoms 
of hydrogen are substituted by one or several metals. 

Potassium Phosphates or Phosphates of Potash. 
— Tliere are three of these phosphates formed by replac- 
ing one, two, or three hydrogen atoms of phosphoric 
acid by jootassium, viz. : KH2PO4, primary or mono- 
potassic phosphate ; K.2HPO4, secondary or dipotassic 
phosphate, and K3PO4, tertiary or tripotassic phos- 
pluite.* Of these salts, the secondary and tertiary phos- 
phates exist largely (to the extent of 40 to 60 per cent) 
in the ash of the kernels of wheat, rye, maize, and other 
bread grains. Tlie potassium phosphates do not occur 
in commerce ; they closely rescml^le the corresponding 
sodinm-salts in their external characters. 

*Tlie primary j.liosphiitos are ofton dosiprpatod acUl or fiiqicr-phofi' 
phntrs, the secondary iieirtra! pl^osphatcH, and the tertiary basic. p)hos- 
phates. 



148 now CROPS grow. 

Sodium Phosphates, or Phosphates of Soda.^ 

Of these the disoilic plio^phatc^ NaoIIP04, alone needs 
notice. It is found in the drug-stores in the form of 
ghissj' crystals, wliich contain 12 molecules (5G })er cent) 
of water. The crystals become opaqne if exposed to the 
air, from the loss of water. This salt has a cooling, sa- 
line taste, and is very solnble in water. 

Calcium Phosphates, or Phosphates of Lime. 
— Since one atom of calcium replaces two of hydrogen, 
the formulas of the calcium phosphates are written as 
follows : monocalcic or primary plioi^plmte CaIl4P208 ; 
dicalcic or secondary pliospliate, CaIIP04 ; tricalcic or 
tertiary pliospliate, CagPaOg.* Both the secondary and 
tertiary phosphates probably occnr in plants. Tlie sec- 
ondary is a white crystalline powder, nearly insoluble 
in water, but easily soluble in acids. In nature it is 
found as a urinary concretion in the sturgeon of the Cas- 
pian Sea. It is also an ingredient of guanos, and proba- 
bly of animal excrements in general. 

The tricalcic phosplicde, or, as it is sometimes termed, 
hone-pliosjiliate, is a chief ingredient of the bones of ani- 
mals, and constitutes 90 to 05 per cent of the ash or 
earth of bones. It may be formed by adding a solution 
of lime to one of sodium phosphate, and appears as a 
white precipitate. It is insoluble in pure water, but dis- 
solves in acids and in solutions of many salts. In the 
mineral kingdom tricalcic phosphate is the chief ingre- 
dient of apatite and pliosphorite. These minerals are 
employed in the preparation of the commercial super- 
jdiospliates now consumed to an enormous extent as a 
fertilizer. Plain superphosphate is essentially a mixture 
of sulphate of lime with the three phosphates above no- 
ticed ai.d with free phosphoric acid. 

The Phosphates of Magnesium, Iron, Alumin- 
ium and Manganese, are bodies insoluble in water. 



* These formula^ corresjioiid to 2 molecules of phosphoric acid, 
—IlergOg, with 2 and 4 H-atoms replaced by Ca. 



TnE ASn OF PLA'N'TS. 149 

that occur in very small proportion in the ashes of plants 
and in soils, but are important ingredients of some 
fertilizers. 

The Chlorides are all characterized by their ready 
solubility in water. The Chlorides of Calcium and Mag- 
nesium are deliquescent, i. e., they liquefy by absorbing 
moisture from the air. The Chlorides of Potassium and 
Sodium alone need to be described. 

Potassium Chloride, or Muriate of Potash, 
KCl, 71.5. — This body may be jjroduced either by expos- 
ing metallic i)otL]ssium to chlorine gas, in which case the 
two elements unite together directly ; or by dissolving 
caustic potash in hydrochloric acid. In the latter case 
water is also formed, as is expressed by the equation 
KTTO + liCl = KCl + IPO. 

Potassium chloride closely resembles common salt in 
ap])earancc, solubility in water, taste, etc. It is now an 
important article of commerce and largely consumed as 
a fertilizer. It is also often present in the ash and in 
the juices of plants, especially of sea-weeds, and is like- 
wise found in most fertile soils. 

Chloride of Sodium, NaCl, 58.5. — This substance is 
common or culinary salt. It was formerly termed muri- 
ate of soda. It is scarcely necessary to speak of its oc- 
currence in immense quantities in the water of the ocean, 
in saline springs, and in the solid form as rock-salt, in 
the earth. Its properties are so familiar as to require no 
description. It is rarely absent from the ash of plants. 

Besides the salts and compounds just described, there 
occur in the living plant other substances, most of which 
have been indeed already alluded to, but may be noticed 
again connectedly in this place. 

These compounds, being destructible by heat, do not 
appear in the analysis of the ash of a plant. 

Nitrates. — Nitric acid (the compound by which ni- 
trogen is chiefly furnished to plants for the elaboration 



150 now CROPS OROw. 

of tlic albumiioid principles) is not nnfrequently pres- 
ent as a nitrate in the tissues of tlie plant. It usually 
occurs there as potassium nitrate (niter, saltpeter), 
KNO3. 

Tlie properties of this salt scarcely need descrii)tion. 
It is a white, crystalline body, readily soluble in water, 
and has a cooling, saline taste. When heated witli car- 
bonaceous matters, it yields oxygen to them, and a defla- 
gratio7i, or rapid and explosive combustion, results. 
Touch-jxiper is paper soaked in solution of niter and 
dried. The leaves of the sugar-beet, sunflower, tobacco, 
and some other plants, frequently contain this salt, and, 
when burned, the nitric acid is decomposed, often witli 
sliglit deflagrjition, or glowing like touch-paper, and the 
alkali remains in tlie ash as carbonate. The characters 
of nitric acid and the nitrates are noticed at length in 
*' How Crops Feed." See also p 

Oxalates, Citrates, Malates, Tartrates, and salts 
of other less common organic acids, are generally to bo 
found in the tissues of living plants. On burning, tlic 
metals with which they were in combination — potassium 
and calcium, in most cases — remain as carbonates. 

Ammonium Salts exist in minute amount in some 
plants. What particular salts thus occur is uncertain, 
and special notice of them is unnecessary in this chapter. 

Since it is possible for each of the acids above described 
to unite witli each, of the bases in one or several propor- 
tions, and since we have as many oxides and chlorides as 
there are metals, and. even more, the question at once 
arises — v/Jiich of the 60 or more compounds that may thus 
be formed outside the plant do actually exist within it ? 
In answer, we must remark that while most or all of them 
may exist in the plant but few have been proved to exist 
as such in the vegetable organism. As to the state in 
which iron and manganese occur, avc know little or noth- 
ing, and we cannot always assort positively that in a given 



TUE ASH OF PLANTS. 151 

])liiiit potassium exists iis pliospliutc, or sulpliatc, or car- 
bonate. We judge, indeed, from the predominance of 
potassium and phos2)lioric acid in the asli of wheat, that 
potassium phosphate is a large constituent of this grain, 
but of this we are scarcely certain, though in the absence 
of evidence to the contrary we are warranted in assuming 
these two ingredients to be united. On the other hand, 
calcium carbonate and calcium sulphate have been discov- 
ered by the microscope in the cells of various plants, in 
crystals whose characters are unmistakable. 

For most purposes it is unnecessary to know more than 
that certain elements are present, without paying atten- 
tion to their mode of combination. And yet there is 
choice in the manner of representing the composition of 
a plant as regards its ash-ingredients. 

We do not indeed so commonly speak of the calcium 
or the silicon in the plant as of lime and silica, because 
these rarely-seen elements are much less familiar than 
their oxides. 

Again, we do not speak of the sulphates or chlorides, 
when we desire to make statements which may be com- 
pared together, because, as has just been remarked, we 
cannot always, nor often, say what sulphates or what 
chlorides are present. 

In the })aragra])hs that follow, wliich are devoted to a 
more particular statement of the mode of occurrence, rd- 
iUive aJjundancc, special functiojis, and iiidispensdhilHy 
of the fixed ingredients of plants, will be indicated the 
customary methods of denning them. 

§2. 

QUAInTITY, distribution, and variations of the ASH" 

INGREDIENTS. 

The Ash of plants consists of the various acids, oxides, 
and salts, that have been noticed in § 1, which are fixed 
or non-volatile at a heat near redness. 



152 now CKOPS gkovv. 

Ash-ingredients are always present in each cell of every 
plant. 

Tlie ash-ingredients exist partly in the cell-wall, in- 
crusted or imbedded in the cellulose, and partly in the 
phisma or contents of the cell (see p 249). 

One portion of the ash-ingredients is soluble in water, 
and occurs in the juice or sap. This is true, in general, 
of the salts of the alkali-metals, and of the sulphates and 
chlorides of magnesium and calcium. Another portion 
is insoluble, and exists in the tissues of the plant iu the 
solid form. Silica, the calcium phosphates and the mag- 
nesium compounds, are mostly insoluble. 

The ash-ingredients may be separated from the volatile 
matter by burning or by any process of oxidation. In 
burning, portions of sulphur, chlorine, alkalies, and phos- 
phorus may be lost, under certain circumstances, by vola- 
tilization. The ash remains as a skeleton of the plant, 
and often actually retains and exhibits the microscopic 
form of the tissues. 

The Proportion of Ash is not Invariable, even ir 
the same kind of plant, and in the same part of the plant. 
Different kinds of plants often manifest very marked dif- 
ferences in the quantity of ash they contain. The fol- 
lowing table exhibits the amount of ash in 100 parts (o| 
dry matter) of a number of plants and trees, and in theii 
several parts. In most cases is gi ven an average pro2)ortion 
as deduced from a large number of the most trustworth)/ 
examinations. In some instances are cited the extreme 
proportions hitherto put on record. 

rROPORTlONS OF ASH IN VARIOUS VEGETABLE MATTERS.* 



\lox\ clover G.7 

White " 7.2 

Tiniotliy 7.1 

I'otatoes 5.1 

Sii^ar beet, 1G.3— 18.G 17.5 

Field beet, 14.0—21.8. 18.2 



ENTIRE PLANTS, ROUTS EXCEPTED. 

Average. Average^ 

Turnips, 10.7— 1!».7.. 15.5 

("iirrot, 15.0— l::l.;5 17.1 

Hops !).!) 

Hemp 4.6 

Flax 4.3 

Heath 4.5 



* These figures are eo])ie(l uiiohanjjjerl from the, old edition, and may 
differ from later averages, but are approximately correct. 



THE ASll OF PLAKTS. 



153 



HOOTS AND TUliEKS. 



Potatoes, 2.6—8.0 4.1 

Suyar bc(>t, 2.'J— CO 4.4 

Field buet, 2.S— 11.3 7.7 



Turnip, G.O— 20.9 12.0 

Carrot., 5.1—10.9 8.2 

Articlioke 5.2 



STKAW AND STEMS. 

Wheat, 3.8— G.9 5.4 | Peas, G.5— 9.4 '7.9 

Kye, 4.9—5.0 5.3 Beans, 5.1 — 7.2 G.l 

Oiits, 5.0—5.4 5.3 Flax 3.7 

Barley 6.8 | Maize 5.5 

GKAINS AND SEED. 

Wheat, 1.5—3.1 2.0 Buckwheat, 1.1—2.1 1.4 

Rye, l.G— 2.7 2.0 Peas, 2.4—2.9 2.7 

Oats, 2.5—4.0 3.3 Beans, 2.7—4.3 3.7 

Barley, 1.8—2.8 2.3 Flax, 3.G 

Maize, 1.3—2.1.... 1.5 , Sorghum 1.9 

WOOD. 

Beech 1.0 | Red Pine 0.3 

Birch 0.3 White Pine 0.3 

Grape 2.7 [Fir 0.3 

Apple 1.3 I Laj-cli 0.3 



BAKK. 



Birch 1.3 

Red Pine 2.8 

White Pine 3.3 



Fir 2.0 

Walnut.......... G.4 

Canto tree 34.4 



From the above table we gather : — 

1. That different plants yield different quantities of 
ash. It is abundant in succulent foliage, like that of the 
beet (18 per cent), and small in seeds, wood, aud bark. 

2. That diff'ereiit parts of the same plant yield unlike 
proportions of asli. Thus the wheat kernel contains 2 
per cent, while the straw yields 5.4 per cent. The ash 
in sugar-beet tops is 17.5 ; in the roots, 4.4 per cent. 
In the ripe oat, Arcndt found {Das Wachsthtim der 
Haferpjlanze, p. 84), 

III the three lower joints of the stem... 4.6 i^er cent of ash. 

In the two niidiUe joints of tlie stem 5.3 " " 

In the one upper joint of the stem G.4 " " 

In the three lower leaves lo.l " '* 

In tlie two upper leaves — 10.5 " " 

In the ear 2.6 " " 

3. We further find that, in general, tlte upper and 
outer parts of the plant contain the most ash-ingredi- 
ents. In the oat, as we sec from the above figures of 
Arendt, the ash increases from the lower portions to the 
upper, until we reach the ear. If, however, the ear be 



154 HOW CROPS GROW. 

dissected, we sliull find tluit its outer purts are richest in 
ash. Norton found 

In the husked kernels of brown oats. ... 2.1 per cent of ash. 

In the husk of brown oats 8.2 " " 

In the chaff of brown oats ID.l " " 

Norton also found tliat the top of the oat-leaf gave 
16.22 per cent of ash, while the bottom yielded but 13. GG 
per cent. {Am. Jour. Science, Vol. Ill, 1847.) 

From the table it is seen that wood (0,3 to 2.7 per 
cent) and seeds (1.5 to 3.7 per cent) — lower or inner 
parts of the plant — are j^joorest in asli. The stems of 
herbaceous plants (3.7 to 7.9 2:»er cent) are next richer, 
while the leaves of herbaceous plants, which have such 
an extent of surface, are the richest of all (G to 8 per 
cent). 

4. Investigation has demonstrated further that the 
same plant in different stages of groioth varies in the pro- 
portions of ash in dry matter, yielded both by the entire 
plant and by the several organs or parts. 

Tlie following results, obtained by Norton, on the oat, 
illustrate this variation. Norton examined the various 
parts of the oat-plant at intervals of one week through- 
out its entire period of growth. He found 

Leaves. Stctn. Knots. Chaff. Grain unhusked 

June 4... 10..S 10.4 

June 11 10.7 <J.8 

Jun^^ 18 ;j.() 1).3 

June 2.") 10.'.) 1».I 

July 2 11.;] 7.8 4.0 

July y 12.2 7.8 4.3 

JulylG.... ...12.G 7.'J G.O 3.3 

July 23 10.4 7.<J 10.0 'J.l 3.6 

July 30 1G.4 7.4 9.0 12.2 4.2 

Aug. 10.0 7.0 10.4 13.7 4.3 

Aug. 13 20.4 0.0 10.4 18.0 4.0 

Aug. 20 21.1 0.6 11.7 21.0 3.0 

Aug. 27 .....22.1 7.7 11.2 22.4 3.5 

Bcpt. 3 20.9 8.3 10.7 27.4 3.0 

Here, in case of the leaves and chaff, we observe a coii= 
stant increase of ash^ while in the stem there is a con- 



THE ASn OF PLANTS. 155 

stant decrease, except at the time of ripening, when these 
relations are reversed. The knots of the stem preserved 
a pretty uniform ash-content. The unhusked grain at 
tirst suffered a diminution, then an increase, and lastly a 
decrease a2,ain. 

Arendt found in the oat-plant fluctuations, not in all 
respects accordant with those observed by Norton. 
Arendt obtained the following proportions of ash : 





3 louver 

joints of 

stem. 


2 mi (Idle 

joints of 

stem. 


Upper 
joint of 
stem. 


Longer 

lea ves. 


Upper 
leaves. 


Ears. 


Entire 
plant. 


June 18.. 


4.4 








9.7 


7.7 




8.0 


June 30., 


2.5 




2.9 


3.5 


9.4 


7.0 


3.8 


5.2 


July 10.. 


3.5 




4.7 


5.2 


10.2 


6.9 


3.0 


5.4 


July 21.. 


,....4.4 




5.0 


5.5 


10.1 


9.7 


2.8 


5.2 


July 31.. 


.....6.4 




5.3 


6.4 


10.1 


10.5 


2.6 


5.1 



Here we see that the ash increased in the stem and in 
each of its several parts after the first examination. The 
lower leaves exhibited an increase of fixed matters after 
the first period, while in the upper leaves the ash dimin- 
ished toward the third period, and thereafter increased. 
In the ears, and in the entire plant, the ash decreased 
quite regularly as the ])Lint grew older. Pierre found 
that the proportion of ash of the co\zii {Brassica olera- 
cea) diminished in all parts of the plant (which was 
examined at five periods), except in the leaves, in which 
it increased. (Jnhresberinht ilher Agriculturclmnie, III, 
p. 122.) The sugar-beet (Bretschncider) and potato 
(Wolff) exhibit a decrease of the per cent of ash, both in 
tops and roots. 

In the turnip, examined at four periods, Anderson 
{Trans. High, and Ag. /S'oc, 1859-Gl, p. 371) found the 
following per cent of ash in dry matter : 

.Jvly 7. 

Leaves ..,,..,..,,.,. 7.8 

Bulbs................ ...,17.7 

In this case, the as!i of t]ic leaves increased during 
about half the period of growth from 7.8 to '■30.6^ and 



Aug. 11. 


Sept. 1. 


Oct. 5. 


20.6 


18.8 


16.2 


8.7 


10.2 


20.9 



156 now CROPS grow. 

thence diminished to 16.2. The ash of the bulbs fluc- 
tuated ill the reverse manner, falling from 17.7 to 8.7, 
then rising again to 20.9. 

In general, the proportion of ash of the entire plant 
diminishes regularly as the plant grows old. 

5. The influence of the soil and season in causing the 
proportion of ash of the same kind of plant to vary, is 
shown in the following results, obtained by Wunder 
Versuchs-Stationen, IV, p. 206) on turnip bulbs, raised 
during two successive years, in different soils. 

In sandy soil. In loamij soil. 

/ \ t \ 

1st year. 2d year. 1st year. 2d. year. 
Per cent of ash 13.9 11.3 i).l 10.9 

6. As might be anticipated, different varieties of the 
same plant, grown on the siime soil, take up different 
quantities of non-volatile matters. 

In five varieties of potatoes, cultivated in the same soil 
and under the same conditions, Herapath {Qu. Jour. 
Chem., Soc. II, p. 20) found the percentages of ash in 
dry matter of the tuber as follows : 

VAKIETY OF POTATO. 

White Prince's Axhridge Forty- 

Airple. Beauty. Kidney. Mai/jAe. fold. 
Ash percent... 4.8 3.6 4.3 3.4 3.9 

7. It has been observed further that different individ- 
uals of the same variety of i}lant,gY{)\N\wg side by side, 
on the same soil (in the same field, at least), contain dif- 
ferent proportions of ash-ingredients, according as they 
are, on the one hand, healthy^ vigorous plants, or, on the 
other, iveah and stunted, Pierre {Jalires'bericlit iiicr 
Agriculturchemie, III, p. 125) found in entire colza 
plants of various degrees of vigor the following percent- 
ages of ash in dry matter : 

In extremely feeble plants, 1856 S.O per cent of ash. 

1\\ very feeble plants, 1857 .9.0 " " 

ni feeble plants, 1857 11.4 " " 

In stron.y- i)lants, 1857............ .....11.0 " " 

In extremely strong plants, 1857. ......... .14.3 " " 



THE ASH OF PLA:NTS. 157 

Pierre attributes the larger per cent of ash in the 
strong plants to the relatively greater quantity of leaves 
developed on them. 

Similar results were obtained by Arendt in case of oats. 
Wunder ( Versuchs-St., IV, p. 115) found that the leaves 
of small turnip-plants yielded somewhat more ash per 
cent than large plants. The former gave 19.7, the lat- 
ter 1G.8 per cent. 

8. The reader is prepared from several of the foregoing 
statements to understand partially the cause of the vari- 
ations in the proj^ortion of ash in different specimens of 
the same kind of plant. 

The fact that different parts of the plant are unlike in 
their composition, the upper and outer portions being, in 
general, the richer in ash -ingredients, may explain in 
some deo:ree why different observers have obtained differ- 
ent analytical results. 

It is well known that very many circumstances influ- 
ence the relative development of the organs of a plant 
In a dry season, plants remain stunted, are rougher oi; 
^ the surface, having more and harsher hairs and prickles^ 
if these belong to them at all, and develop fruit earlier 
than otherwise. In moist weather, and under the influ- 
ence of rich manures, plants are more succulent, and the 
stems and foliage, or vegetative parts, grow at the ex- 
pense of the reproductive organs. Again, different vari- 
eties of the same plant, which are often quite unlike in 
their style of development, are of necessity classed to- 
gether in our table, and under tlie same head are also 
brought together plants gathered at different stages of 
growth. 

In order that tlie w^heat plant, for example, should 
always have the same percentage of ash, it would be nec- 
essary that it should always attain the same relative de- 
velopment in each individual ))art. It must, then, 
always grow under the same conditions of temperature. 



158 HOW CHOPS GROW. 

light, moisture, and soil. This is, however, as good as 
impossible, and if we admit the wheat plant to vary in 
form within certain limits without losing its proper char- 
acteristics, we must admit corresponding variations in 
composition. 

The difference between the Tuscan wheat, which is 
cultivated exclusively for its straw, of which the Legliorn 
liats are made, and the '^•'pedigree wlieat" of Mr. Ilallett 
(Journal Roy. Ag. Soc. Eng., Vol. 22, p. 374), is in 
some respects as great as between two entirely different 
plants. The hat wlieat has a short, loose, bearded ear, 
containing not more than a dozen small kernels, while 
the pedigree wheat has shown beardless ears of 8f inches 
in length, closely packed with large kernels to the num- 
ber of 120 ! 

Now, the hat wheat, if cultivated and propagated in 
the same careful manner as has been done with the pedi- 
gree wheat, would, no doubt, in time become as prolific 
of grain as the latter, while the pedigree wheat might 
perhaps with greater ease be made more valuable for its 
straAV than its grain. 

We easily see then, that, as circumstances are perpet- 
ually making new varieties, so analysis continually finds 
diversities of composition. 

9. Of all the parts of plants, the seeds are the least lia- 
hle to vary in composition. Two varieties or two indi- 
viduals may differ enormously in their relative propor- 
tions of folingo, stem, chaff, and seed ; but the seeds 
themselves nearly agree. Thus, in the analysis of G7 
specimens of the wheat kernel, collated by the author, 
^ the extreme percentages of ash vv^ere 1.35 and 3.13. In 
GO specimens out of the G7, the range of variation fell 
between 1.4- and 2.3 per cent. In 42 the range was from 
< '"p^: 1.7 to 2.1 per cent, while the average of the whole was 
^-f -> 2.1 per cent. 
^_^ In the stems or straw of the grains, the variation is 
"> 




O 



THE ASH OF PLAISTTS. 159 

mnch more considerable. Wheat-straw ranges from 3.8 
to G.9 ; pea-straw, from 6.5 to 9.4 per cent. li\ fleshy 
roots, the variations are great ; thus turnips range from 
G to 21 per cent. The extremest variations in ash-con- 
tent are, however, found, in general, in the succulent 
foliage. Turnip tops range from 10.7 to 19.7; potato 
tops vary from 11 to near 20, and tobacco from 19 to 27 
per cent. 

Wolff {Die Naturgesetzliclien Gnindlagen dcs Acher- 
haus, 3 Anil., p. 117) has deduced from a large number 
of analyses the following averages for tliree important 
classes of agricultural plants, viz. : 

Grain. Straw. 

Cereal crops ..... 2 per cent. 5.25 per cent. 

Legumnious crops 3 " " 5 " " 

Oil-plants ...4 " " 4.5 «' " 

More general averages arc as follows (Wolff, loc. cit.) : 



Annual and biennial 2^la7its. 

Seeds 3 per cent 

Stems 5 " " 

Roots ..4 



Perennial plants. 

Seeds 3 jier cent. 

Wood 1 " " 

Bark 7 " " 



Leaves 15 " " I Leaves ....10 

We may conclude this section by stating three propo- 
sitions which are proved in part by the facts that have 
been already presented, and which are a summing up of 
the most important ^^oiuts in our knowledge of this sub- 
ject. 

1. Ash-ingredients are indispensable to the life and 
growth of all plants. In mold, yeast, and other plants 
of the simplest kind, as well as in those of the higher or- 
ders, analysis never fails to recognize a proportion of 
fixed matters. We must hence conclude that these are 
necessary to the primary acts of vegetation, that atmos- 
pheric food cannot be assimilated, that vegetable matter 
cannot be organized, except with the cooperation of those 
substances which are invariably found in the ashes of the 
plant. This proposition is demonstrated in the most 
conclusive manner by numerous synthetic experiments. 



IGO HOW CROPS GROW. 

It is, of course, impossible to attempt producing a plant 
at all without some asii-ingredients, for the latter are 
present in all seeds, and during germination are trans- 
ferred to the seedling. By causing seeds to sprout in a 
totally insolubh) medium, we can observe what happens 
when the limited supply of fixed matters in the seeds them- 
selves is exhausted. Wiegtnann & Polstorf {Preisschrift 
iller die unorfjanisclien BestancUheilo der Pflanzen) plant- 
ed 30 seeds of cress in fine phitinum wire contained in a 
platinum vessel. The contents of the vessel were moist- 
ened with distilled water, and the whole was placed under 
a glass shade, which served to shield from dust. Through 
an aperture in the shade, connection was made with a gas- 
ometer, by which the atmosphere in the interior could be 
renewed with an artificial mixture, consisting, in 100, of 
21 parts oxygen, 78 parts nitrogen, and 1 part carbonic 
acid. In two days 28 of the seeds germinated ; afterwards 
they developed leaves, and grew slowly with a healthy ap- 
pearance during 26 days, reaching a height of two or 
three inches. From this time on, they refused to grow, 
began to turn yellow, and died down. The plants were 
collected and burned ; the ash from them weighed pre- 
cisely as much as that obtained by burning 28 seeds like 
those originally sown. This experiment demonstrates 
'most conclusively that a plant cannot grow in the absence 
of those substances found in its ash. The development 
of the cresses ceased so soon as the fixed matters of the 
seed had served their utmost in assisting the organization 
of new cells. We know from other experiments that, had 
the ashes of cress been applied to the plants in the nbove 
experiment, just as they exhibited signs of unhealthiness, 
they would have recovered, and developed to a much great- 
er extent. 

II. The proportion of ash-ingredients in the plant is 
variable within a narrow range, but cannot fall below or 
exceed certain limits. The evidence of this proj)osition 



THE ASn OP PLANTS. 161 

is to bo gathered both from tlic tal)le of ash-percentages 
and from experiments like that of Wicgmann & Polstorf, 
above described. 

III. We have reason to believe that each part or organ 
(each cell) of the plant contains a certain, nearly invaria- 
ble, amount of fixed matters, which is indispensable to the 
vegetative functions. Each part or organ may contain, 
besides, a variable and unessential or accidental quantity 
of the same. What portion of the ash of any plant is es- 
sential and what accidental is a question not yet brought 
to a satisfactory decision. By assuming the truth of this 
proposition, we account for those variations in the 
amount of ash which cannot be attributed to the causes 
already noticed. The evidences of this statement must 
be reserved for the subsequent section. 

§ 3. 

SPECIAL COMPOSITION OF THE ASH OF AGIIICULTL'KAL 

PLANTS. 

The result of the extended inquiries which have been 
made into the subject of this section may be convenient- 
ly presented and discussed under a series of propositions, 
viz. : 

1. Among the substances which have been described 
(§ 1) as the ingredients of the ash, the following are in- 
vr.riably present in all agricultural plants, and in nearly 
all parts of them, viz.: 

fPotash, KjO' rriiloriue, CI. 

Poda, Na,0. Sulphuric acid, SO... 

Eases <i Lime, CaO. Acids <^ Phosplioric acid, P,0,. 
I M-X2nesia, MgO. SiUcic acid, SiO,. ' 

LOxide of iron, FejOg. ^Carbonic acid, CO,. 

2. Different normal specimens of the same kind of 
IDlant have a nearly constant composition. The use of 
the word nearly in the above statement implies what has 
been already intimated, viz., that some variation is noticed 
in the relative proportions as well as in the total quantity 

11 



1G2 HOW CROPS GROWc 

of ash-ingredicnts occurring in plants. This point will 
shortly be discussed in fall By taking the average of 
many trustworthy ash-analyses we arrive at a result which 
does not differ very widely from the majority of the in- 
dividual analyses. This is es2)ecially true of the seeds of 
plants, which attain nearly the same development under 
all ordinary circumstances. It is less true of foliage and 
roots, whose dimensions and character vary to a great 
extent. In the following tables (p. 164-170) is stated the 
composition of the ashes of a number of agricultural 
products which have boen repeatedly subjected to analy- 
sis. In most cases, instead of quoting all the individual 
analyses, a series of averages is given. Of these, the first 
is the mean of all the analyses on record or obtainable by 
the writer,* while the subsequent ones represent either 
the results obtained in the examination of a number of 
samples by one analyst, or are the means of several single 
analyses. In this way, it is believed, the real variations 
of composition are pretty truly exhibited, independently 
of the errors of analysis. 

The lowest and highest percentages are likewise given. 
These are doubtless in many cases exaggerated by errors of 
analysis, or by impurity of the material analyzed. Chlo- 
rine and sulphuric acid are for the most part too low, be- 
cause they are liable to be dissipated in combustion, while 
silica is often too high, from the fact of sand and soil ad- 
hering to the plant. 

In two cases, single and doubtless incorrect analyses by 
Bichon, which give exceptionally large quantities of soda, 
are cited separately. 

A number of analyses that came to notice after making 
out the averages are given as additional. 

* At tlie time of preparing the first edition of this hook, in 1868. More 
reoent analyses are C()nii);iratively few in nuniher, excepting tliose of 
wlieat (grain and straw) l)y Lawes & Gilhert, and do not differ essen- 
tially from tliose given. The nnmerons very ineorrect ash-analyses, 
pnhlished by Dr. E. Emmons and Dr. J. H. Salishnry, in the Natural 
History of New York, and in the Trans, of the New York State Agricul- 
tural Society, are not includofJ. 



THE ASH OF PLANTS. 163 

Tlio following tn])lc includes both the kernel and straw 
of Wheat, Rye, Barley, Oats, Maize, Rice, Buckwheat, 
Beans, and Peas ; the tubers of Potatoes ; the roots and 
tops of Sugar-Beets, Field-Boets, Carrots, Turnips, and 
various parts of the Cotton Plant. 

For the average composition of other plants and vege- 
table products, the reader is referj-ed to a table in the ap- 
pendix, p. 409, compiled by Prof. Wolff, of the Royal 
Agricultural Academy of Wiirtemberg. That table in- 
cludes also the averages obtained by Prof. Wolff for most 
of the substances, cotton excepted, whose composition is 
represented in the pages immediately following. 

In both tables the carhjnic acid, CO^, which occurs in 
most ashes, is excluded, from the fact that its quantity 
varies according to the temperature at which the ash is 
prepared'. 

The following is a statement of the various Names and 
Symbols that are or have been currently applied to the 
Ash-Ingredients in Chemical Literature. The changes 
that have been made from time to time, both in symbols 
and in names, are the results of progress in knowledge or 
of attempts to improve nomenclature : 



Synonyms. 
Potash, Potassa, Potassium Oxide, Potassic Ox'ido. 
Sorta, Sodium Oxide, Sodic Oxide. 
Magnesia, Magnesium Oxide, Magnesic Oxide. 
Lime, Caleiimi Oxide, Calcic Oxide, 
n-on Oxide, Peroxide of n-on, Sesquioxide of Iron, 
Ferric Oxide. 

PO5 P20,-; Pliosplioric Acid, Anliydrons Pliosphoric Acid, 

Plios]>lioric Anliydide, Pliosphorus Pentox- 
ide. Phosphoric Oxide. 
Sulphuric Acid, Anhydrous Sulphuric Acid, Sul- 
phuric Anhydride, Sulphur Trioxide, Sul- 
phuric Oxide. 
SiOo SiOo Silicic Acid, Anhydrous Silicic Acid, Silicic An- 

hydride, Silicon Dioxide, Silicic Oxide, Silica 
Silex. 
Carbonic Acid, Anhydrous Carbonic Acid, Car- 
bonic Anhydride, Carbon Dioxide, Carbcnic 
Dioxide. 



Ollpr 


Newey 


Syrihols. 


Symbols, 


KO 


K.,0 


NaO 


Na,0 


MgO 


MgO 


CaO 


CaO 


FesO,, 


Fe203 



SO, so. 



CO, COo 



164 



now CROPS GROW. 

















"■^^ 
















>-.= 
























p 








-T-^ 








l-H 








^H 








o 








C5 _; 
























^3 =y 






o c i 


cf^ 








^1 I 










m 










O +-'2^ 


O 


O 






K >-.7^, ^ S cc ^ 






^ O -H O +H CC '-' 

1^ N r5 t-S O >^,^ cc 




O 






^^^So^^ 2 




Is 








IK ^ 

Oi tH ,-1 




M COCO^ r-l 


ii 






>~. <M <N 




i^ TH-* t,<] 


co^S 


CO 








rt - ' ^ .s 

5 ^ 


w 




^1 






t^ ^ CO « - rfl 
5(H ^ tf-l 


,-hCOIOOO «» 

C4H (H 


CO 


C0C0;*OiCOg^ _oc;-g- 


%> 
m'-" 






o o o 


O 11 


w 


o a; ;'.'^ 


^ t 






a; (-^^j 0) 


<D i-^+j 


O '-^,^ "^ c3 


+-^ -H 








fcJD +^ x ic 


M *^ M 




Wl -^ ^ S*^ 






Ph > 

„ IC-*!^ t-Or-lrH '^ 

" ddo ddddPi 


2. . . S2K 
rH ddcq 1-^ 


^ I^^s 

^ |.^2S^ 

<i i-qMop^ 

CO. l-H '^'^'^ <=i^ 

i-h't-h ddio dd 








fH f^ 
1/ O 


C Oi 


U ^ 


;ii 


H 




(3 






c3 


H 


Oi-HOOCOOOCOO '"' 


o ic>o iC o o 


^ 


Tt<COl-HOl-HOl-Ht-©l-Ht~ 




S 


3 




(M l-H l-H Tj< o -+< 


P£i 


CIOOt-H-+ii-H©0<10C<lCOCO 
<M(NC0C^C0COC<)C0(MC0C0 


m « 


o 




Ph 
1-; ic c<j rH c; -j^ ■^ 

<dd>o\ d d e4 l-H 






'OS a 


il 


ill 


c4 ddco 


p^ 


o©oocoooo(N©co-H^in 
c4r-5<?4cor-?ddTjHdTHi-H 


.1^ ID 


,-i,-HOOlOO-t<'^<0 


O O ?0 ^ tH 00 


0DrHT)JCiC0'*©00«5CO-tJ 

cqc4c<iioo6ddddd 2 

COC0COC0(MC0(MC0-#CO^ 


«.2 






lO CO lO 1-1 lO l-H 


-^ 

M 


^E'^ 




•rti Tt< ■* •* <M »n 


S 2 








O 


S 3 




00 O t-; © CO Oi 

t6d> d'daid' 


d rHd?4 




00 1-; cj 1-^ l-H -i; o lo lO 

ad •rH l-H d (N l-H © d 


•H 
rH iH 


1 

l-H 


o 












^2 






^.t^ 


H 






(MC^iC-^COOOiMO 


C5 O l-H C5 CO CO 




C0"HHt^C0a0Ot:-(M-rJH|~-.rH 


^2 


in 
O 


2 




eoiMfOiMcocoooofo 


CO CO <N lO l-H lO 




CM(N<MCslC0^©-#O4C^ie0 


Ph 

o 


1 -iW 


COCiCOlCt-;C^eOfOt-- 

cld-NrHC^ic^iddd 


O lO <M CO l-H Tt< 

l-H r-H C-i i-i d -ti 


C<)r)HOI-;C^aDCOt-;i-HCqoO 

o6o6t-^rHo6d-*-jHoi>:o 


o^ 


f<i ^ 




l-HrHi-HrHi— iT— t 1— (rH 






l-H l-H l-H 


H d" 


o 


















r5 




(Mocqt-ocoooo 


COCOi-H(N©00 




»Ci-HC»OOI>-©CDCiOO©CO 


■S !^ 




o 




COCSCOOKMTfOiOO 


■*O(M00©© 




COC<lCOC<lCOt-©OOOlCO 


*l^ '-H 




m 




rH 


(M 




'"' 


S«2 




1 ^ 


C0OTt<Ot-00©'+ll-- 


00 l-H lO TtH -!!< lO 


cqt-ic^co©ooco©©© 


f ^* 








i-HOi^O&COI.-OOOC^ 


00 C2 CO in ci t^ 




rHOOOOO<Mt^COi-HCOl^t^ 


ajp^ 




PhCS 




COCOCO(NCOC<I(MCOCO 


iMOq CO(N CO 




(M (M rH TH (N rH rH CO rH rH 






+3 . 






















.^O 




^■•^'^. 




C0©rt<O Oi-H 


© © T-H O O t- 




rH©(MlClC0000rtH»ClO 


>rr 




'^^< 




(M rH(M J<l i-iCO 


iM (N Cq l-H T-H C<1 




(MC<l!M(N<MrH(MMCqO<l 


* tx 














CJ 



THE ASn OP PLANTS. 



1(35 



o (0 



P -; O 












o 

rn 
Ph OS 



Ph ^ 



c o «5 



T-H T-H O Oi - 



§2 



rf^ CO 00 O ?0 
OO O O 1-5 



■* O O O © 



m o o ^ o bH ic 



w 

H 

_ fo o 00 t-^ |^5 
^ 1-5 t>i ci Ci <N 

<N<N t-H CO 



»0 lO CO ^H ,-» 

O d o o c4 



c-- cc O CO -iH 

CO CO CO rH 00 



C-l C lO o t- 
t- I- I- -J- GJ 



lO O C5 CO C^ 

c<i (m' c4 d CO 



O CO lO CO CO 

id d -H ci -H 



CO cood^iH 





i^H -rH 


rl 


f^ 


Zj 0) 


^ 


f^ 


;3^ 


f-l 


Cl 


OJ 0; 




J2 


O i/ 




t-5 - - 


h-J 




Oi iJ 


r-, 


t; 


a; a: 
















rr; 


O o 






C/2CO 





O) 



OJ 



05 

00 O 



coco^ 



© 



<4-l CC . ^ 

O bJ3bJ3 . (D 
<ij O f-i f-i Jh 
bct^.2P5 

;7, >irt ojP-i ;2(jH 



c^ 



; cc ci; cc ^ 



-1^ ;^ |JH h-! ^_crj pq _!J H-l M H^ W 



4J 05 



O r- C3 



»o O IC OlO 

dc6'*d'* 



COCOrHCOOlO^.OOOOO 



rHi-l(MOC0 ;i<M 



^ ^ ^. c-. 



35 O iM 1-^ O IC 

'w ^ ^ ^ 0^- <>• o iri 



OOt-Or-lOO-flOlOO'tlOb- 



< ■* ■^ ■*! CO ■* CO o 



00 lO O C5 O; CS O OO 'l^ O lO o 

ii'S'di d ii rH oi d r-5 d d C5 



icascocoojcoc^corH 
c<idTHrHr-5dcoc<5co 



CO CO 
'd d 



OCO-+OCOOO(Mt-;COOCOO 

lOcoidt-^co-t'din-iHi-^di-it-^ 



05 1- ic o N in lo ci 0C50M 

CO 1-5 1-^ d CO CO rH CO ci':£i^c6 



co-ticocoococot-t-t-ot^co 



IC rH COCO t^ O CO rH 

rH (N r-5r-5 i-5rHrHC<J 



lOiC 






0^ o .■ 

<|t-jNP5 



? tJO 

3£ 



d s3 c3 



cacor-5coc6c4rHCO 



coo J$ 



1-1 

P^ 
W 

t-'-rcocooococo 
^ cocoo4d-i^(Ndco 

i_i ICIOO-^IOIO-^O 

P^ 



(MCOtNOrHOOOOSq 
COrHt-^ldi-lOOt- 



c-j t- c-1 ■* CO T)< ca CO 
T-5 rH -* (m' -(5 CO -H -1^ 



»Ct~-mC0OrHirit-; 

»cdc^d'^T)5i^d 



t-iC(NC<IC0-+iiO-+i 



mor+<co(Mt~c<>o 



o 




Ph 






OJ 






4- 


P 






? 


OT 


r: 


W 


u 


0) 




(J 


rr 


eJ 


cc 


4-S 


^ 


n 


o 


r-t 










^ 


CJ 


^ 


w 


4- 


>i 


c^ 








0; 


< 


K 


cu 






N 


c« 






K- 


0) 


* 


Q 



166 



now cRors grow. 















n o 
•S o 








^° 
















C8 O 




















"-"fl 




a; 




































O a:) 




•4^ 

o 




^ s 














.21 fl 

■— 'M to 




o 

to 2 

bn g 




o <id 

+H 

CO CO 

^7i a 


















. ooco bJ3 
























in lOrH 














CO ''I 




to '"'^ ?r! 




JO '-HrH Ci 






CO 




. 




1^ rnrH 
Vi COCO 




CO O r^ 

i:^ a; 2 

e3- - - fcJO S 










>3 




S d 




"^ - - - ^ .S 






C3 "* - tJO (D 






03 




/:: -H 








5 ^ s 




a c3 +^ 






-11 




o^ : 




<J g 






<j ^.^ 




^ 








jH -1^ in I- .c o 2 




rH O >3 


N 


inocDg- 00 






o 


hJ 




° 1 






< 


o So 






M 


M 


CO 




&J0 +^ CO 




W) H '^ Vi 


fee -^i to fcJC 




H 
1— 1 


gc3 




>> 


h4 


n S2 

5 35 


h5 






?2 S - ?^ 






C <D 


^ 


tT -^ 




o a 


^ 


rfl 00 rH t- (N O IC 


m 


in Tt< rH 00 o o 


< 


rH 00O-t<CD 


r^ -rH 


Oth 


H 


MrH 


04 


rH rH O rH rH O O 


:4 


rHCOrHOOCD 




rH OiGCiC^ 


O '^ 


(^ 




< 










^ 










c3 


W 


i§ 


W 


t- 


00 O iC rt« C5 (N CD 




00 -^ooOTOio 


< 


rH CO f CD CO CD 




;^i 


K 


o 


*fl 


OOOrlOOiM 


i^; 


OOOOOCM 


Pi 


^ O OO ^ CO CD 
CO CO O CO t- CO 


CO 


^ 
w 


+3 






3 

Ph 




<1 




CO 




o 






;:i! 




O 






CO t- rH t- O O ■* 

»# (N t-^ in CO o si 


P5 


c<i CO "* h- CO -i; CO 

CO CO -^ rH rH CO CO 


H 


in !M -i; t-; CD O 

c-i CO T-i o in CO 




















<1 










HH 


Orfi C5 




^ t-(N 




cococoo-f o-f 




CD in rH 05 rH (M t- 


CO O C-' Oq C5 CD 




p:^ 


TJH-* CO 




O O 05 
Ut: -ti -t< 




« CO CO CO CO <N -? 




"# CO (M rH (r~ rH C^ 

CO CO CO CO (N •* CO 


^ 


in CD rt* iM 00 CO 










^eo T5 




CO O CO O C^ O 00 










^ - 




<M CO CO O O 


t- m O rH CO t- 


.;::; 3 




c-c- 




rH'Mi-l 




O rH O O O O CO 




O O O O rH 




OOOOrH O 


^- 






















o 


oo o 


t- CO 00 


■>* CO O CD O (M C^ 


CO in CO rt< rH •^ CO 


CO O CD t- 00 I- 


c 




Tj< rl L-- 




<X>rti »-H 




in ■* CO o t- c<i CO 




CO ■* 00 in CO CO CD 




inminiMoo^ 


"^ 
















^~' 














Tt< CO in 














tjo.3 


t-CO<M 


CO O rH t- (M CO IM 


CO I- t- 03 rH O 


in -f CD O "M CO 


■^ ?, 




O O rH 




OtN •+ 




I- CO l^ CO 00 lO (M 




t- in CO 00 in 'N 




(N ^) !M O in rH 


J52 








rH O C<l 




y-t 




'"' 






o 


COfNOO 


rH C5 O in CO O C5 


oo t-coococq 


CD t-OOOOt- 




lO lO iC 




OCiCO 




CO O l^ rH CO O C^ 




CD rH rH OJ O (M O 
rH CN 




rH O CO O t- © 


, 


Ol-"* 


t^ CO -ti 


C5 CO in 'f CO c<i i- 


in •+! t- O 00 CD rH 


m CD CO CO t~ -t< 


4J .^ 

O 0} 
PhcS 












o (>5 o 'M to -f in 




CO m -f -t" o CO CO 
CO CO •^ CO c<i m -f 




^ ^ rt ,-H -^ -O 








(MC<I 




-t< tT CO -t< CO C-5 -H 






r^ r^ T^ r^ T^ 




(M^ CO 


rH rH 1-1 


t- -f n 


t-oco t-co 


•^< CO C5 rH 


„-=^ 




0CC5 t- 




(Nr-lr=l 




<N CslCN 




eo CO '^ c^i ■* 




in CO CO CO 



THE ASn OF PLANTy. 



167 



•^ "Zt '^ 

•J- -^ -11 



^ O o 












■i2 o 



*_ '-'5 lO ^2 
CO ^ 

II i 

r- CD -I-' 

?^ S2S .-• 

H 






be o' 





L. fl^ 








O i 


+J 


^ ^ 






r3 


^o 


c3 


^ 


W) 


"-1 


d 


-M 


. w 


o 


r' CO 


H 






3o 


j^ 


bfj^ 


^ 


Oi^ 


e3 



1^ rt o 
/2- - 



C5 C5 



t- '^l lO GO 



0) 

CI:: 

0) 



to © 



i^ c; CO 5 

^ .a -S 






a- 



:: tx) 

03 



o 



O 0) 



ji ^ ^ ^ oj^ 






c4 o4 






fi| CO 
t^ CO CO 

t-rr; re iX! 

3W<! ^ 






03 cd 



ecc5 

rH CO 



o o coio o o **< 

CO CO CO t-H t-^ -^ H 



^ . . > . 



■JT} 




>^ 






CTj 








H 




m 




X uO<Ni-i 


^ 


^ t-COCOC5 lO 




ic M ■*! o CO -ti 


w 


00 


IC 




P3 


■X O irt O 


04 


"iH c-^ 05 1- r? 00 


O 


O O CC) fM -t< rH 

Tti lO r)< Tj* lO CO 


N 
1— 1 


CO 


-a 


»o 


< 


C5 XIO 




t-COCOC5 


,-ICO 


CO -fH 01 <M -t< 


<M 




CO 




1-1 O (N 


CO<MO^-f 


rHCO 




CO CO CO (M tM 




»o 


lO 























M 








CO -X n* lO 




lOOrHO<M(M 




i-H (M CO CI CO CO 




CO 


o 






lO CO t- -fi 




-fi O ■* "ti <M t- 




»+l lO Ol rH t- CO 




00 




tH 
rH 






CC C10 




c:5a) 


C^l o 




CO O 00 t- t- o 




rfl 




c^. 






o o^.-i 




TlO 


0<M 




rH 7-1 rH O C-l O 




c^ 








O LO O CD 














00 




tl 






t-coo 1HC0.-I 


rfl O rH Ci OO O 






t- lO O I- 

rH 




L^ t- Ci t- 


tH 




I- t^ 00 -f 00 o 




o 

rH 




00 

T-l 






OC0-t< 




-t< o o o 


t- rH 




CO CO CO CO LO 




t- 




CO 






(N(M CO 




C) CO Ol T-H 


rHCO 




CO CO CO CI iCi 




lO 




CO 






O O CO 




rH O lO CO 


rH t~- 




-f CO 1 - CTi t- 




>o 




oq 






(MOO 




-tl -t< CO rt< 


rH lO 




CO -ti C3 01 -l^ 

rH 








(M 






'+00CO 




O O *+! CO 00 O 




lO -t< Ol (M rH 




CO 




CO 






lOClO 
.-( CO 




— ( -M in o 

CslrHrHCO 


C5 O 
rH<M 




c:3 rH C-J C-1 CO 
<N <N rH rH Ol 




CO 

CO 




CO 





!NC5COC<l 
O"^ COti5 



lO o 
JO';)? 



OJ C5 

CO id 



• ( 

So 




-u 








bCo 








CO 




4) . 




■drt 




tf o 








SO 




c3 ., "'•.'■ 




•Jo ■< 2 


CO 

o 

CO 


r 03^ 


>s 


Ph^O 


c3 " 




< 




(MO-1 


CO 


(M<M 


cu 










•rH 




0) fj» 




bJD .• 


C3 




<1 


-1^ ii 


(M CO CO CO 




(MrH 
O 


Ol 


^-«.2 


bf) 


■^ rr rr. 


03 


%%>: 




CD- - - 


iJ'hrcS 


> 


o—H S 


<c| 


j-^WjiJ 


CO CO CO t^ O C<1 C5 


CO t~ CO t- O CO o 




rH rH 


»+< t- CO CO CO -f CO 


>C lO »0 ■*! O rH CO 


rH Ol CO t- 00 O CO 


CO CO in t^ o CO 00 


rH O rH CO t- -M b- 


t- O -tl 00 rH CO -tH 




rH 


-t* -tH CO 00 o in 00 


rH rH rH O O CO rH 


OOOlOrH 


CO-tHCO 


CO lO '-^ r^ 


I- I-CO 


CO CO -+ CO 




CI CO CO m CO o o 


t- t- CO O CO CO 01 




rH^I 




■^^ 1 


t~- CO CO CO o r-i CO 1 


ifi id id 00 o -tH o 1 




iM 


»tH !M t- rH tH 1ft ^^ 


rH CO ~^ id O CO ^ 


iMOJO^rH 


COc<| 


nn fli -H 


-f* CO 


■<1< L^ ijO P3 l-< 1 



? c 2 ^ 

tin cj ^ 



CO 


o 


s 


cu 




-1-^ 


K 


D 


O 














l^H 












+H 






fc? 


c;j 


;^ 


r-H 






W 


r; c3 




,U 






„ 














(1) 


r^ 


ro 


+-> 
















;-f 












a; 




g 




S 




r-; 










tf 


!^ 


To 


o 




>• 


O 03 


(H 




w 


W 


o 


O 




4- 




CM 


4-9 
CJ 






N=+H 






ci; 




o 






;= 




S 


'r-t 




ri 




(U 


<V 




flj 


fH 


orr! 




P4 


.•oi 


0) 


rH 
(1) 




0) 


OC 


+- 


c3 


rH 


^ 


;5 


o3 


>. 


lO 


Oi 


;:2 


^ 


rH 


o 
N 

4H 

a; 


c3 

PH 


+H 

o 


c3 

CO 


6 




•X) 


CO 


^ 




-1- 


3 

c3 


ill 


o 

3 


O 




w 


w 


!h 


Til 


rH 


111 




OJ 


zn 


CD 
CI; 


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now CHOPS GROW. 



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THE ASH OF PLANTS. 



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170 



IIOV/ CROPS GKOW. 



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1 





THE AlJil OL' PLANTS. 171 

The composition of tlio Jlsli of n iuim];cr of oniiiic^ry 
crops is ooncisoly cxhibitod in tlio oubjoiiied gunoml stiito- 
mont. 

Alkalies, tivsla.^""''- ic AcUL '^'''^«- iv Acid. (^'^^ormo. 

CEKExVLS— 

CJi-aiu*-.... 30 12 3 4G 2 2.5 1 

Straw... 13—27 3 7 5 50—70 2.5 2 

Legumes— 

Kernel... 14 7 5 35 14 2 

Straw... 27—41 7 25—39 8 5 2— G 6—7 

Root Cuors— 

Roots.... GO 3—9 G— 12 8—18 1—4 5—12 3—9 

Tops.... 37 3— IG 10—35 3—8 3 G— 13 5—17 
GitASSES— 

Inllower.. 33 4 8 8 35 4 5 

3. Different parts of any ]_)lant usually exhibit decided 
differences in the composition of thoir ash. This fact is 
made evident by a comparison of the figures of the table 
above, and is more fully illustrated by the following)- anal- 
yses of the parts of the mature oat-plant, by Arendt, 1 to 
G (Die Ilaferj'Jlanze, p. 107), and Norton, 7 to 9 {Am. 
Jour. jScL, 2 Scr. 3, 318). 

1 2 34 5G78 9 

Loirer Middle Up} er L->n-nr Upiiev Ears. Cliajf. llusk Kernel 
iStcm. iStem. iiteni. L aves. Leaves. husked. 

Potash H1.2 C8.3 55.9 3G.9 24.8 13.0) 

Foda 0.4 1.5 1.0 0.9 0.4 0.1 j l"'"^ ^^'^ ^1"' 

MaLHiesia 2.1 3.6 3.9 3.8 3.9 8.9) 2.3 8.6 

Liiiie 3.6 5.3 8.6 16,7 17.2 7.3 1 ,1 •> 4.3 5.3 

Oxide of Iron.... 1-0 0.0 0.2 2.7 0.5 trace f ^^-^ 0.3 0.8 

Phospliorie acid. 2.7 1.4 2.7 1.7 1.5 3G.5 J O.G 49.1 

Snlphurie acid.. 0.0 1.3 1.1 3.2 7.5 4.9 5.3 4.3 0.0 

pilica 4.1 9.3 20.4 34.0 41.8 2G.0 G8.0 74.1 1.8 

Clilorine 8.6 11.7 7.4 1.6 2.4 3.8 3.1 1.4 0.2 

The results of Arendt and Norton are not in aU respeets strictly coni- 
p:iral)le, havini; been obtained by dillerent nietliods, but serve well to 
establish the fact in question. 

We see from the above figures that the ash of the lower 
stem consists chiefly of j^otash (81%'). This alkali is pre- 
dominant throughout the stem, btit in the upper parts, 
where the stem is not covered by the leaf sheaths, silica 
and lime occur in large quantity. In the ash of tlie leaves, 
silica, potash, and lime arc the ])rincipal ingredients. In 
the chaff and husk, silica constitutes throe-fourths of tlio 
ash, while in the grain, phosphoric acid appears as thechar- 

*Ex elusive of husk. 



172 HOW CROPS GROW. 

acterlstic ingredient, existing there in connection with a 
large amount of potash (32%) and considerable magne- 
sia. Chlorine acquires its maximum (11.7%) in the mid- 
dle stem, but in the kernel is present in small quantity, 
while sulphuric acid is totally wanting in the lower stem, 
and most abundant in the upper leaves. 

Again, the unequal distribution of the ingredients of 
the ash is exhibited in the leaves of the sugar-beet, which 
have been investigated by Bretschi) eider ( Hoff. JaUreshe- 
riclit, 4, 89). This experimenter divided the leaves of G 
sugar-beets into 5 series or circles, proceeding from the 
outer and older leaves inward. He examined each series 
separately with the following results: 

I. II. III. IV. V. 

Potash 18.7 25.9 32.8 37.4 50.3 

Soda 15.2 14.4 15.8 15.0 11.1 

Chloride of Sodium.... 5.8 6.4 5.8 G.O 6.5 

Lime. 24.2 10.2 18.2 15.8 4.7 

Magnesia 24.5 22.3 13.0 8.9 6.7 

Oxide of Iron 1.4 0.5 0.6 0.6 0.5 

Phosphoric acid 3.3 4.8 5.8 8.4 12.7 

Sulphuric acid 5.4 5.0 5.6 5.2 5,9 

Silica 1.5 0.8 2.7 2.1 1.5 

From these data we perceive that in the ash of the leaves 
of the sugar-beet, potash and phosphoric acid regularly 
and rapidly increase in relation to the other ingredients 
from without inward, while lime and magnesia as ra})idly 
diminish in the same direction. The per cent of the other 
ingredients, viz., soda, chlorine, oxide of iron, sulphuric 
acid, aiitl silica, remains nearly invariable throughout. 

Another illustration is furnished by the following anal- 
yes of the ashes of the various parts of the horse-chestnut 
tree made by ^^KAHi^Ackcrljau, 2. Auf., 134): 

B(rk. Wood. Leaf-stems. Leaves Fiower-stems. Calyx. 

Potash 12.1 25.7 46.2 27.9 63.6 61.7 

Lime.- 76.8 42.9 21.7 29.3 9.3 12.3 

Ma.i,nu"sia 1.7 5.0 3.0 2.6 1.3 5.9 

Suli)liuri<' acid trace trace 3..S 9.1 3.5 trace 

Phosphoric acid 6.0 19.2 14.8 22.4 17.1 16.G 

Silica 1.1 2.6 1.0 4.9 0.7 1.7 

Chlorine 2.8 0.1 12.2 5.1 4.7 2.4 





Green Fruit. 




Ripe Fruit. 


Petals. 


Kernel. 


Green 
Shell. 


Broivn 

Shell. 


G1.2 


58.7 


61.7 


75.9 


54.6 


13.6 


9.8 


11.5 


8.6 


16.4 


3.8 


2.4 


0.6 


1.1 


2.4 


trace 


3.7 


1.7 


1.0 


3.6 


17.0 


20.8 


22.8 


5.3 


18.6 


1.5 


0.9 


0.2 


0.6 


0.8 


3-8 


4.8 


2.0 


7.6 


5.2 



THE ASH OF PLANTS. 173 



Stamens. 

Potash 60.7 

Liine 13.8 

Magnesia 3.1 

Sulphuric acid trace 

Phosphoric acid. . . l'J.5 

. Silica 0.7 

Chlorine 2.8 

4. Similar kinds of plants, and especially the same parts 
of similar plants, exhibit a close general agreement in the 
composition of their ashes ; while plants which are un- 
like in their botanical characters are also unlike in the 
jn-oportions of their fixed ingredients. 

The three plants, wheat, rye, and maize, belong, botan- 
ically speaking, to the same natural order, graminece, and 
the ripe kernels yield ashes almost identical in composi- 
tion. Barley and the oat are also graminaceous plants, 
and their seeds should give ashes of similar composition. 
That such is not the case is chiefly due to the fact, that, 
unlike the wheat, rye, and maize-kernel, the grains of 
barley and oats are closely inyested with a husk, which 
forms a part of the kernel as ordinarily seen. This husk 
yields an ash which is rich in silica, and we can only prop- 
erly compare barley and oats with wheat and rye, when 
the former are hulled, or the ash of the hulls is taken out 
of the account. There are varieties of both oats and bar- 
ley, whose husks separate from the kernel — the so-called 
naked or skinless oats and naked or skinless barley — and 
the ashes of these grains agree quite nearly in composi- 
tion with those of wheat, rye, and maize, as may be seen 
from the table on page 174. 

By reference to the table (p. 166), it will be observed 
that the pea and bean kernel, together with the allied 
vetch and lentil (i). 171), also nearly agree in ash-com- 
position. 

So, too, the ashes of the root-crops, turnips, carrots. 



171 now ciiops Giiovv. 

and beets, exhibit ii geiieriil sin)iliirity of composition, tis 
miiy be seen in tiie tiible (p. 168-0). 

Wheat. lii/e. Maize. iStiiiless JSiiiiles 

Avctaje Aoeiaye Aoeraye outs. barlei/s. 

<>.f "/ '/ All u lysis Anal II s IS 

sevtiiiy-iiine twtnty-one seven l>y Fr. by Fr. 

Analyses. Analyses. Analyses. /6'o ulze. Seluilze. 

Potash 31.3 28.8 27.7 33.4 35.'J 

Soda 3.2 4.3 4.0 1.0 

Magnesia.... 12.3 ll.G 15.0 11.8 13.7 

Lime 3.2 3.9 1.9 3.G 2.9 

Oxide of lion 0.7 0.8 1.0 0.8 0.7 

riiosplioric acid 4G.1 45.6 47.1 4G,9 45.0 

Sulpliiiric acid 1.2 1.9 1.7 

Silica 1.9 2.G 2.1 2.4 0.7 

Chlorine 0.2 0.7 0.1 

The seeds of the oil-bearing plants likewise constitute 
a group whose members agree in this respect (p. 170). 

5. The asli of the same species of plant is more or less 
variable in composition, according to circnmstances. 

The conditions that have already been noticed as in- 
fluencing the proportion of ash are in general the same 
that affect its quality. Of tliese we may sr)ecially notice : 

a. The stage of groAvth of the plant. 

b. The vigor of its development. 

c. The variety of the plant or the relative develo^jment 
of its parts, and 

(I. Tlie soil or the supplies of food. 

a. The stage of groivth. The facts that the different 
parts of a plant yield ashes of different com])ositioii, and 
that the different stages of growth are marked by the 
devc'l(>})juent of new organs or the unequal expansion of 
those already formed, are sufficient to sustain the point, 
now in ([uestion, and render it needless to cite analytical 
evidence. In n, subsequent chapter, wherein we shall at- 
tempt to trace some of the various steps in the progress- 
ive development of the plant, numerous illustrations will 
be adduced (p. 241). 

h. Vigor of devclopincnt. Arendt (Die llaferpfianze, 
p. 18) selected from an oat-field a number of plants in 
blossom, and divided them into three parcels : 1, com- 



2 


3 


•3'J.[) 


42.0 


4.1 


5.6 


8.5 


8.8 


5.8 


4.7 


0.5 


1.0 


5.4 


5.1 


34.3 


30.4 



THE A SIT OF TLA NTS. 175 

posed of very vigorous plants ; 2, of micdiiim ; mid, 3, of 

very weak plants. IIo analyzed the ashes of each parcel, 

with results as below : 

1 

Silifii .27.0 

Sulphuric ticid 4.8 

Phosphoric acid 8.2 

Chlorine G.7 

Oxide of Iron 0.4 

Lime G.l 

Magnesia, Potash and Soda. 45.3 

Here we notice that the ash of the weak plants con- 
tains 15 per cent less of alkalies, and 15 per cent more of 
silica, than that of the vigorous ones, while the propor- 
tion of the other ingredients is not greatly different. ' 

Zoeller {Lichicfs Erndhrung der Vegetahilicyi, p. 340) 
examined the ash of two si')ccimens of clover which grew 
on the same soil and under similar circumstances, save 
that one, from being shaded by a tree, was less fully de- 
veloped than the other. 

Six weeks after the sowing of the seed, the clover was 
cut, and gave tlie following results on partial analysis : 

Shaded clnrer. Unshaded clover. 

Alkalies 54.9 36.2 

Lime 14.2 22.8 

Silica 5.5 12.4 

c. Tlte variety of llie plant or tltc relative dcvelopme?if 
of its parts must obviously influence the composition of 
the ash taken as a whole, since the parts themselves urc 
unlike in composition. 

Herapath {Qu. Jour. Chem. Soc, II, p. 20) analyzed 
the ashes of the tubers of five varieties of potatoes, raised 
on the samiC soil and under precisely similar circum- 
stances. His results are as follows : 

White 

A fjjife. 

Potash G9.7 

Chloride of Sodium. . 

Limo 3.0 

Magnesia 0.5 

I'hof^phoric acid 17.2 

Sulphuric acid 3.6 

Silica 



Prince's 
Beiiuiy. 


A. 


rhriihje 

'idiiey. 


Magpie. 


Forty-fold. 


65.2 




70.6 


70.0 


62.1 










2.5 


1.8 




5.0 


.5.0 


3.3 


5.5 




5.0 


2.1 


3.5 


20.8 




14.9 


14.4 


20.7 


6.0 




4.3 


7.5 


7.9 






0.2 







170 now CROPS GROW. 

d. The soil, or the supplies of food, manures inchided, 
have the greatest influence in varying the proportions of 
the ash-ingredients of the plant. It is to a considerable 
degree tlie character of the soil which determines the 
vigor of the plant and the relative development of its 
parts. This condition, then, to a certain extent, in- 
cludes those already noticed. 

It is well known that oats have a great range of weight 
per bushel, being nearly twice as lieavy, when grown on 
rich land, as when gathered from a sandy, inferior soil. 
According to the agricultural statistics of Scotland, for 
the^ year 1857 {Trans. Highland and Ag. Soc, 1857-9, 
p. 213), the bushel of oats produced in some districts 
weighed 44 pounds per bushel, while in other districts it 
was as low as 35 pounds, and in one instance but 24 
pounds per bushel. Light oats have a thick and bulky 
husk, and an ash-analysis gives a result quite unlike tliat 
of p^ood oats. Ilerapath {Jour. Roy. Ag. Society, XI, 
p. 107) has published analyses of light oats from sandy 
soil, the yield being six bushels per acre, and of heavy 
oats from the same soil, after ^^ warping,"* where the 
produce was 64 bushels per acre. Some of his results, 
per cent, are as follows : 

Light oats. Heavy oats. 

Potash 9.8 13.1 

Soda 4.6 7.2 

Lime 6.8 4.2 

Phosphoric acid 9.7 17.6 

Silica 56.5 45.6 

Wolf! {Jour, far Prakt. Chem., 52, p, 103) has anal- 
ysed the ashes of several plants, cultivated in a poor soil, 
with the addition of various mineral fertilizers. The in- 
fluence of the added substances on the composition of the 
plant is very striking. The following figures comprise 
his results on the ash of buckwheat straw, which grew 

* Thickly covering with sediment from muddy tide-water. 



THE AST! OF PLANTS. 177 

on the unmanurcd soil, and on the «ame, after applica- 
tion of the substances specified below : 

12 3 4 5 6 

Utima- Chloride Nitrate Carbonate Sii]>hate Carbonate 
uared. </ of of <-/ of 

sodium, potash, potash, maijnesia. lime. 

rotash 31.7 21.6 39.6 40.5 28.2 23.i) 

Chlorideof potassivim.... 7.4 26.9 0.8 3.1 6.9 9.7 

Chluride of sodium 4.6 3.0 3.2 3.8 3.4 1.7 

Lime 15.7 14.0 12.8 11.0 14.1 18.6 

Magnesia 1.7 1.9 3.3 1.4 4.7 4.2 

Sulplmric acid 4.7 2.8 2.7 4.3 7.1 3.5 

rhosplioric acid 10.3 9.5 6.5 8.9 10.9 10.0 

Carbonic acid 20.4 10.1 27.1 22.2 20.0 23.2 

Silica 3.6 4.2 4.2 4.2 4.8 5.2 

100.0 100.0 100.0 100.0 100.0 100.0 

It is seen from these figures that all the applications 
employed in this experiment exerted a manifest influ- 
ence, and, in general, the snbstance added, or at least one 
of its ingredients, is found in the plant in increased 
quantity. 

In 2, chlorine, but not sodium ; in 3 and 4, potash ; 
in 5, sulphuric acid and magnesia, and in G, lime, are 
present in larger proportion than in the ash from the 
nnmanured soil. 

6. What is the normal composition of the ash of a 
plant ? It is evident from the foregoing facts and con- 
siderations that to pronounce upon the normal composi- 
tion of the ash of a plant, or, in other words, to ascer- 
tain what ash-ingredients and what proportions of them 
are proper to any species of plant or to any of its parts, 
is a matter of much difficulty and uncertainty. 

The best that can be done is to adopt the average of a 
great number of trustworthy analyses as the approximate 
expression of ash-composition. From such data, how- 
ever, we are still unable to decide what are the abso- 
lutely essential, and what are really accidental, ingredi- 
ents, or what amount of any given ingredient is essential, 
and to what extent it is accidental. Wolff, who appears 
to have first suggested that a j^art of the ash of plants 
12 



178 now cRorr, grow. 

may bo accidental, CTidcavorod to approacli a solution of 
this question by comparing- together the aslies of sam- 
ples of the same plant, cultivated under the same circum- 
stances in all respects, save that they were supplied with 
unequal quantities of readily-available ash-ingredientSo 
The analyses of the ashes of buckwheat-stems, just 
quoted, belong to this investigation. Wolff showed that, 
by assuming the presence in each specimen of buckwheat- 
straw of a certain excess of certain ingredients, and de- 
ducting the same from the total ash, the residuary ingre- 
dients closely approximated in their proportions to those 
observed in the crop which grew in an unmanured soil. 
The analyses just quoted (p. 163) are here ^'corrected" 
in this manner, by the subtraction of a certain per cent 
of tlioso ingredients which in each case Avere furnislied 
to the plant by the fertilizer applied to it. The num- 
bers of the analyses correspond with those on the previ- 
ous page. 

1 2 3 4 5 6 

20jo c. 20 p. c. 25 p. c. 8 5??. c. lR.fi p. r. 

Cliloriile Cnrbonnte Carhmiale S^ilpluifr. C((yl)'^iifitrs 

After (Ir^Hcdon ff oi' of of of rair'nioiii 

of Nothing, po'iis- pntas- po/as- mninir- ni(t(jv<'- 

simn. siiiiii. si'/irt. sinin.. siiiin. 

Totash 31.7 27.0 32..5 33.5 3!).G 2S.0 

Chloride of potassium. 7.4 9.1 1.0 3.9 7.4 11.3 

Chloride of sodium. . 4.6 3.8 4.0 4.7 3.7 1.9 

Lime 15.7 17.3 IG.O 145 15.3 14.6 

Magnesia 1.7 2.4 4.1 1.7 2.3 2.9 

Sid plmric acid 4.7 3,5 3.4 5.4 2.1 4.1 

Phosphoric acid 10.3 11.7 8.1 11.2 11.8 11.7 

Carbonic acid 20.4 20.1 25.9 19.8 21.6 19.3 

Snica 3.G 5.2 5.2 5.3 5.2 G.l 

• 100.0 100.0 100.0 100.0 100.0 100,0 

Tlie cori'cspondence in the above analyses thus ^' cor-= 
rected," already tolerably close, might, as Wolff remarks 
{loc. cit.), be made much more exact Ijy a further correc- 
tion, in which the quantities of the two most variable in- 
gredients, viz., chlorine and sulphuric acid, should be 
reduced to uniformity, and the analyses then be recalcu- 
lated to per cent. 



THE ASn OF TLANTR. 179 

In the first place, however, we arc not warranted 
in assuming that the *' excess" of potassium chloride, 
jjotassium carbonate, etc., deducted in the above analyses 
respectively, was all accidental and unnecessary to the 
plant, for, under the inlluence of an increased amount of 
a nutritive ingredient, the plant may not only mechani- 
cally contain more, but may chemically employ more in 
the vegetative processes. It is well proved that vegeta- 
tion, grown under the influence of large supplies of nitro- 
genouis manures, contains an increased proportion of 
truly assimihited nitrogen as albuminoids, ami do- acids, 
etc. The same may be equally true of the various ash- 
ingredients. 

Again, in the second place, we cannot say that in any 
instance the minimum quantily of any ingredient neces- 
sary to the vegetative acts is present, and no more. 

It must be remarked that these great variations are 
only seen when we compare together plants produced on 
poor soils, i. e., on those which are relatively deficient in 
some one or several ingredients. If a fertile soil had 
been employed to support the buckwheat plants in these 
trials, we should doubtless have had a very different 
result. 

In 1859, Metzdorf {Wilda's Centralblatt, 1862, II, p. 
367) analysed the ashes of eight samples of the red- 
onion potato, grown on the same field in Silesia, but dif- 
feren tly m anured. 

Without copying the analyses, we may state some of 
the most striking results. The extreme range of varia- 
tion in potash was 5^ per cent. The ash containing the 
highest i^ercentage of potash was not, however, obtained 
from potatoes that had been manured vv'ith 50 pounds of 
this substance, but from a parcel to which had been ap- 
plied a poudrette containing less than three pounds of 
potash for the quantity used. 

The nnmanurcd potatoes were relatively the richest in 



180 now CROPS GROW. 

lime, phosphoric acid, and sulphuric acid, although sev^ 
eral parcels were coi)ioasly treated with manures contain- 
ing considerable quantities of these substances. These 
facts are of great interest in rcfei'ence to the theory of 
the action of manures. 

7. To what extent is each ash-ingredient essential, 
and how far may it be accidental ? Before chemical 
analysis had arrived at much perfection, it was believed 
that the ashes of the plant were either unessential to 
growth, or else were the products of growth — were gener- 
ated by the i)lant. 

Since the substances found in ashes are universally dis- 
tributed over the earth's surface, and arc invariably pres- 
ent in all soils, it is not possible, by analysis of the ash 
of plants growing under natural conditions, to decide 
whether any or several of their ingredients are indispen- 
sable to vegetative life. For this pur})ose it is necessary 
to institute experimental inquiries, and these have been 
prosecuted with great painstaking, and with highly val- 
uable results. 

Experiments in Artificial Soils. — The Prince Salm- 
Ilorstmar, of Germany, was one of tlie first and most 
laborious students of this question. His plan of experi- 
ment was the following : The seeds of a plant were sown 
in a soil-like medium (sugar-charcoal, pulverized quartz, 
purified sand) which was as thoroughly as possible freed 
from the substance whose special influence on growth 
was the subject of study. All other substances presum- 
ably necessary, and all the usual external conditions of 
growth (light, warmth, moisture, etc.), were supplied. 

The results of 195 trials thus made with oats, wheat, 
barley, and colza, subjected to the influence of a great 
variety of artificial mixtures, have been described, the 
most important of which will shortly be given. 

Experiments in Solutions. — Water-Culture.— 
Sachs, W. Knop, Stohmann, Nobbe, Siegert, and others 



THE ASn OF PLANTS. 



181 



havo likewise studied this subject. " Their method was 
like that of Prince Salm-Horstmar, except that the plants 
were made to germinate and grow independently of any 
soil; and, throughout the experiment, had their roots im- 
mersed in water, containing in solution or suspension the 
substances whose action was to be observed. 

Water-Culture has recently contributed so much to our 
knowledge of the conditions of vegetable growth, that 
some account of the mode of conducting it may be prop- 
erly given in this place. Cause a num- 
ber of seeds of the plant it is desirod to 
experiment upon to germinate in moist 
blotting-paper, and, when therootshave 
become an inch or two in length, select 
the strongest seedlings, and support 
them so that the roots shall be immersed 
in water, while the seeds themselves 
shall be just above the surface of the 
liquid. 

For this purpose, in case of a single 
maize plant, for example, provide a 
quart cylinder or bottle with a wide 
mouth, to which a cork is fitted, as in 
Fio". 22. Out a vertical notch in the 
cork to its center, and fix therein the 
stem of the seedling by packing with 
cotton. The cork thus serves as a sup- 
port of the plant. Fill the jar with pure 
water to such a height that when the 
cork is brought to its place, the seed, S, 
shall be a little above the liquid. If 
the endosperm or cotyledons dip into the water, they 
will speedily mould and rot ; they require, however, to be 
kept in a moist atmosphere. Thus arranged, suitable 
warmth, ventilation, and illumination alone are requi- 
site to continue the irrowth until the nutriment of the seed 




Fig. 22. 



182 now CROPS grow. 

is iic.'irly oxlumstcd. As rc^i^ards illumination, this should 
be as full as possible, for the foHage ; but the roots should 
be protected from it, by enclosing the vessel in a shield of 
black paper, as, otherwise, minute parasitic alga3 would 
in time develop upon the roots, and disturb their functions. 
For the first days of growth, pure distilled water may ad- 
vantageously surround the roots, but, when the first green 
leaf appears, they should be placed in the solution whose 
nutritive pow^r is to be tested. The temperature should 
be properly proportioned to the light, in imitation of what 
is observed in the skillful management of conservatory or 
house-plants. 

The experimenter should first learn how to produce 
large and well-developed plants l)y aid of an appropriate 
liquid, before attempting the investigation of other prob- 
lems. For this purpose, a solution or mixture must be 
prepared, containing in proper proportions all that the 
plant reqnircs, save what it can derive from the iitmos- 
phere. Tlio experience of Nobbo and Siegert, Knop, 
Wolff, and others,* supplies valuable information on this 
point. Wolff has obtained striking results with a variety 
of plants in using a solution made essentially as follows: 
Place 20 grams of the fine powder of well-burned liones 
with a half pint of water in a large glass flask, heat to boil- 
ing, and add nitric acid cautiously in quantity just suffi- 
cient to dissolve the bone-ash. In order to remove any 
injurious excess of nitric acid, pour into the boiling liq- 
uid a solution of pure potassium carbonate until a slight 
permanent turbidity is produced; then add 11 grams of 
potassium nitrate, 7 grams of crystallized magnesium sul- 
phato, and 3 grams of potassium chloride, with water 
cnougii to make the solution up to the bulk of one liter- 
Wolff's solution, thus prepared, contains in 1000 parts 
as follows, exclusive of iron: 



* Soo cspociaUy ToWonn (irryumhrrrf's Jour, fur Landwirthschaft^ 1882, p, 
537) lor liiU and "concise instructions. 



THE AiSll OJb" PLANTS. 183 

I'hosphoric iicid ..........'......... 8.2 

Lilac ..10.5 

PuLasli <j.l 

MagiiL'siii , 1.4 

Suli)limic a.citl ..- 2.2 

Clilorinc O.'J 

Nitric acid , ., . .2'j.7 

Solid Matters , .,..,,.... C2 

Water ..... yyy 

1000 

For use, dilute 15 or 20 c. c. of the above solution with 
water to the bulk of a liter and add one or two drops of 
strong solution of ferric chloride. 

The solution should be changed at first every week, and, 
55 the plants acquire greater size, their roots should be 
transferred to a larger vessel filled with solution of the 
;5ame strength, and the latter changed every 5 or 3 days. 

It is important that the water which escapes from the 
jar by evaporation and by transpiration through the plant 
should be daily or of tener replaced, by filling it with jiure 
water up to the original level. The solution, whose prep- 
aration has been described, may be turbid from the sepa- 
ration of a little calcium sulphate before the last dilution, 
as well as from the preci])itation of phosphate of iron on 
adding ferric chloride. The former deposit may be dis- 
solved, though this is not needful; the latter will not dis- 
solve, and should be occasionally put into suspension by 
stirring the li({uid. When the plant is half grown, fur- 
ther addition of iron is unnecessaiy. 

In this manner, and with this solution, WoUf produced 
a maize })iant live and three quarters feet high, and ecpuil 
in every respect, as regards size, to plants from similar 
seed, cultivated in the field. The ears were not, however, 
fully developed when the experiment was interrupted by 
the plant becoming uidiealthy. 

With the oat his success was better. Four plants were 
brought to maturity, having 4G stems and 1535 well-de- 
veloped seeds. (Vs. St., VIII, ppa90-215.) 



184 HOW CROPS GROW. 

In similar experiments, Nobbe obtained buckwheat 
plants, six to seven feet liigli, bearing three hundred 
plump and perfect seeds, and barley stools with twenty 
grain-bearing stalks*. {Vs. St., VII, p. 72.) 

In water -culture the composition of the solution is suf- 
fering continual alteration, from the fact that the plant 
makes, to a certain extent, a selection of the matters pre- 
sented to it, and does not necessarily absorb them in the 
proportions in which they originally existed. In this 
way, disturbances arise which impede or become fatal to 
growth. In the early experiments of Sachs and Knop, 
in 18G0, they frequently observed that their solutions 
suddenly acquired the odor of hydrogen sulj^hide, and 
black iron sulphide formed npon the roots, in consequence 
of which they were shortly destroyed. This reduction of 
a sulphate to a sulphide takes place only in an alkaline 
liquid, and Stohmann was the first to notice that an acid 
liquid mioht be made alkaline by the action of living 
roots. The plant, in fact, has the power to decompose 
salts, and by appropriating the acids more abundantly 
than the bases, the latter accumulate in the solution in 
the free state, or as carbonates with alkjiline properties. 

To prevent the reduction of sulphates, the solution 
must be kept sliglitly acid, if needful, by addition of a 
very little free nitric acid, and, if the roots blacken, thoy 
must be washed with a dilute acid, and, after rinsing with 
water, must be transferred to a fresh solution. 

On the other hand, Kiihn has shown that when am- 
monium chloride is employed to supply maize with nitro- 
gen, this salt is decomposed, its ammonia assimilated, and 
its chlorine, which the plant cannot use, accumulates in 
the solution in the form of hydrochloi'ic acid to such an 
extent as to prove fatal to the plant ( Henneberif s Journal, 
1864, pp. IIG and 135). Such disturbances are avoided by 
employing large volumes of solution, and by frequently 
renewing them. 



THE ASH OF PLANTS. 185 

The concentration of the solution "is by no means a 
matter of indiiference. While certain aquatic phints, as 
sea- weeds, are naturally adapted to stroni^- saline solutions, 
agricultural land-plants rarely succeed well in water cul- 
ture, Avhen the liquid contains more than to^oo of solid 
matters, and will thrive in considerably weaker solutions. 

Simple well-water is often rich enough in plant-food to 
nourish vegetation perfectly, provided it be renewed suffi- 
ciently often. Sachs's earliest experiments were made 
with well-water. 

Birnerand Lucanus, in 18G4 ( Vs. SL,Ylll, 154), raised 
oat-plants in well-water, which in respect to entire weight 
were more than half as heavy as plants that grew simul- 
taneously in garden soil, and, as regards seed-production, 
fully equalled the latter. The well-water employed con- 
tained but 3oVo of dissolved matters, or in 100,000 parts: 

rotash 2.10 

Lime 15.1!) 

Magnesia 1.50 

Phosphoric acid 0.16 

Sulphuric acid 7.50 

Nitric acid •. 6.00 

Silica, Chlorine, Oxide of iron traces 

Solid Matters o2.3G 

Water 9y,%7.64 

100,000 

On the other hand, too great dilution is fatal to growth. 
IS^obbe ( V;<. SL, VIII, 337) found that in a solution con- 
taining but Toooo of solid matters, ivhich tuas continualhj 
renewed, barley made no progress beyond germination, 
and a buckwheat ])!ant, which at first grew rapidly, was 
soon arrested in its development, and yielded but a few 
ripe seeds, and but 1.74G grm. of total dry matter. 

While water-culture does not provide all the normal 
conditions for tiie growth of land plants — the soil having 
important functions that cannot be enacted by any liquid 
medium — it is a method of producing highly-developed 
plants, under circumstances which admit of accurate con- 



l^G now CHOPS GUOW. 

trol and great variety of alteration, and is, tlioreforo, of 
the utmost value in vegetable physiology. It has taught 
important facts which no other means of study could re- 
veal, and promises to enrich our knowledge in a still 
more eminent degree. 

Potassium, Calcium, and Magnesium as soluble 
Salts, Phosphorus as Phosphates and Sulphur as 
Sulphates, are absolutely necessary for the life of 
Agricultural Plants, as is demonstrated by all the ex- 
periments hitherto made for studying their influence. 

It is impossible to recount here in detail the evidence 
to this effect that is furnished by the investigations of 
Salm-Horstmar, Sachs, Knop, Nobbe, Birner and Luca- 
nus, and others ( Vs. St., VIII, p. 128-161). 

Some 01 the experimental proof of this statement is 
strikingly exhibited by the figures on Plate T, copied 
from Nobbe, showing results of the water-culture of 
buckwheat in normal nutritive solutions and in solutions 
variously deficient. 

Is Sodium Essential for Agricultural Plants? 
This question has occashmed much discussion. A glance 
at the table of ash-analyses (pp. 1G4-170) will show that 
the range of variation is very great as regards this alkali- 
metal. The older analysts often reported a considerable 
l)roportion of sodium oxide, even 20% or more, in the ash 
of seeds and grains. In most of the analyses, however, 
sodium oxide is given in much smaller (piantity. The 
average in the ashes of the grains is less than 3 i)er cent, 
and in not a few of the analyses it is entirely icautiny. 

In the older analyses of other classes of agricultural 
plants, especially in root crops, similarly grejit variations 
occur. Some uncertainty exists as to these older data, for 
the reason that the estimation of sodium by the processes 
customarily emi)loyed is liable to great inaccuracy, espe- 
cially with the inexperienced analyst. On the one hand, 
it is not or was not easy to detect, much less to estimate, 



THE ASn OF PLANTS. 187 

minute traces of sodium when mixed with much potassi- 
um ; while, on the other hand, sodium, if present to the 
extent of a per cent or more, is very Uable to be estimated 
too high. It has therefore been doubted if these high 
percentages in tlie asli of grains are correct. 

Again, the processes formerly employed for preparing 
the ash of plants for analysis were such as, by too elevated 
and prolonged heating, might easily occasion a partial 
or total expulsion of sodium from a material which prop- 
erly should contain it, and we may hence be in doubt 
whether the older analyses, in which sodium is not men- 
tioned, are to be altogether depended upon. 

The later analyses, especially those by Bibra, Zoeller, 
Arendt, Bretschneider, Ritthausen, and others, who have 
employed well-selected and carefully-cleaned materials for 
their investigations, and who have been aware of all the 
various sources of error incident to such analyses, must 
therefore be appealed to in this discussion. From these 
recent analyses we are led to precisely the same conclu- 
sions as were warranted by the older investigations. Here 
follows a statement of the range of percentages of sodium 
oxide in the ash of several field crops, according to the 
newest analyses: 

SODIUM OXIDK (SODA) TX LATEK ASII-ANALYSfiS. 

Ash <if Wheat kcnicl, none, Bibra, to 5% liil>ra. 

" " " " 0.28% Lawos&GiU-)ert," 1.1S% 

" " Potato tixbor, 'lone, { ^fJ^JJ.^^'^^^^^^^^^ " 4% WollT. 

«' " Barlpv keniol I ^'^^ Bibra, ' „ ^p, ( Bibra. 

iiaiiey Kemei, j 2% Zoeller, *'/'^ \ Veltmann. 
" " " " " 7% Zoeller. 

" " Sno-nrbopt I 4% Ritthausen, " 29.-S% Ritthausen. 

Gu^.u ucer,, | r^j^ Bretsehneidor, " l(\.Q,% Bretseluieider. 

*' " Turnip root, 7.7% Anderson, " 17.1% Anderson. 

Although, as just indicated, sodium in some instances 
}*as been found wanting in the wheat kernel and in po- 
tato tubers, it is not certain that it was absent from other 
parts of the same plants, nor has it been proved that 
sodium is wanting in any entire vlant which has grown 
on a natural soil. 



188 HOW CROPS GEOW. 

Weinbold found in the ash of the stem and leaves of 
the common live-for-ever {Sedum telephiinn) no trace oE 
sodium detectable by ordinary means ; while in the ash 
of the roots of the same plant there occurred 1.8 per 
cent of its oxide ( Fs. St., TV, p. 190). 

It is possible then that, in the above instances, so- 
dium really existed in the plants, though not in those 
parts which were subjected to analysis. It should be 
added that in ordinary analyses, where sodium is stated 
to be absent, it is simply implied that it is present, if at 
all, in too small a quantity to admit of determining by 
the usual method, while in reality a minute amount may 
be present in all such cases.* 

The iiuLil result of all the analytical investigations 
hitherto made, with regard to cultivated agricultural 
plants, then, is that codium is an extremely variable in- 
gredient of the ash of plants, and though generally pres- 
ent in some proportion, and often in large proportion, 
has been observed to be absent in weighable quantity in 
the seeds of grains and in the tubers of potatoes. 

Salm-IIorbtmar, Stohmann, Knop, and Nobbe & Sie- 
gert have contributed experimental evidence bearing on 
tliis f[UCstion. 

The investi2:ations of Salm-IIorstmar were made with 
great nicety, and especial attention was bestowed on the 
influence of very minute quantities of the various sub- 
stances employed. He gives as the result of numerous 
experiments, that, for wheat, oats, and barley, in the 
early vegetative stages of growth, 8odinm, while advan- 
tageous, is not essential, but that for the perfection of 
fruit an appreciable thougli minute quantity of this ele- 
ment is indispensable. ( Vcrsuche unci Reszdtate fiber 
die NaliTung dcr Pjiauzen, pp. 12, 27, 29, 36.) 



*Tho metho^ls of spectral analysis, Iw whioh ^^^^^^^-^^ of a pram of 
sofliuni oxide mav 1>(^ rletected, denionstrato tliis element to l)e so nni- 
versnlly distriltntef' tliat it is next to impossible to find or to prepare 
anything that is free from it. 



THE ASH OF PLANTS. 180 

Stohmann's single experiment led to the similar con- 
clusion, that maize may dispense with sodium in the 
earlier stages of its growth, but requires it for a full 
development. [Henneherg^s Jour, far Landwirtliscliaft, 
1862, p. 25.) 

Knop, on the other hand, succeeded in bringing the 
maize plant to full perfeotion of parts, if not of size, in a 
solution which was intended and asserted to contain no 
sodium. {Vs. SL, III, p. SOL) Nobbe & Sie^-ert came 
to the same results in similar trials with buckwheat. 
Vs. St., IV, p. 339.) 

Later trials by N"obbe, Schroder and Erdmann, and by 
others, confirm the conclusion that sodium may be nearly 
or altogether dispensed with by plants. 

The buckwheat represented in Plate I vegetated for 3 
months in solutions as free as possible from sodium, with 
the exception of VI, in which sodium was substituted 
for potassium. 

The experiments of Knop, Nobbe, Siegert and others, 
while they prove that much sodium is not needful to 
maize and buckwheat, do not, however, satisfactorily 
demonstrate that a little sodium is not necessary, because 
the solutions in which the roots of the plants were im 
mersed stood for months in glass vessels, and couLl 
scarcely fail to dissolve some sodium from the glass. 
Again, slight impurity of the substances which were em- 
ployed in making the solution could scarcely be avoided 
without extraordinary precautions, and, finally, the seeds 
of these plants might originally have contained enough 
sodium to supply this substance to the plants in appro= 
ciable quantity. 

To sum up, it appears from all the facts before us : 

1. That sodium is never totally absent from plants, 
and that, 

2. If indispensable, but a minute amount of it is 
requisite. 



190 now CROPS GROW. 

3. That the foliage and succulent portions of the plant 
may include a considerable amount of sodium that is not 
necessary to the plant ; that is, in other words, accidental. 

Can Sodium replace Potassium? — The close simi- 
larity of potassium and sodium, and the variable quanti- 
ties in which the latter especially is met witii in plants, 
have led to the assumption that one of these alkali-metals 
can take the i3lace of the other. 

Salm-Horstmar and Knop & Schreber fir:t demon- 
strated that sodiam cannot entirely take the place of 
potassium — that, in other words, potassium is indispen- 
sable to plant life. Plate I, VI, shows the development 
of buckwheat during 3 months, in Nobbe, Schroder & 
Erdmaun's water-cultures, when, in a normal nutritive 
solution, potassium is substituted by sodium, as com- 
pletely as is practicable. 

Cameron concluded, from a series of experiments which 
it is unnecessary to describe, that, under natural condi- 
tions, sodium nvdj 2^artially replace potassium. A partial 
replacement of this kind would a])pear to be indicated 
by many facts. Thus, Herapath has made two analyses 
of asparagus, one of the wild, the other of the culti- 
vated plant, both gathered in flower. The former was 
rich in sodium, the latter almost destitute of this sub- 
stance, but contained correspondingly more potassium. 
Two analyses of the ash of the beet, one by Wolff (1), the 
other by Way (2), exhibit similar differences : 

Asparaous. Field Beet. 

Wild. Cultivated. 1. 2, 

Potassium oxide 18.8 50.5 57.0 25.1 

Sodium oxide 1G.2 trace 7.3 34.1 

Calcium oxide ...28.1 21.3 5.8 2.2 

Magnesium oxide 1.5 4.0 2.1 

Clilorine 10.5 8.3 4.9 34.8 

Sulplmr trioxide 9.2 4.5 3.5 3.6 

Phosphorus pentoxidc 12.8 12.4 12.9 1.9 

SiUca.... 1.0 3.7 3.7 1.7 

These results go to show — it being assumed that only a 
very minute amount of sodium, if any, is absolutely nee- 



THE ASH OF PLANTS. 191 

essary to plant-life — that tlie sodium whicli appears to 
replace potassium is accidental, and that the replaced 
potassium is accidental also, or in excess above what is 
really needed by the plant, and leaves us to infer that the 
quantity of these bodies absorbed depends to some ex- 
tent on the composition of the soil, and is to the same 
degree independent of the wants of vegetation. 

Alkalies in Strand and Marine Plants. — The 
above conclusions apply also to plants which most com- 
monly grow near or in salt water. Asparagus, the beet 
and carrot, though native to saline shores, are easily ca- 
pable of inland cultivation, and indeed grow wild in com- 
parative absence of sodium compounds. 

The common saltworts, Salsola, and the samphire, 
Salicornia, are plants which, unlike those just men- 
tioned, seldom stray inland. Gobel, who has analyzed 
these plants as occurring on the Caspian steppes, found 
in the soluble part of the ash of the Salsola hracldata 
4.8 per cent of potassium oxide, and oO.o per cent of 
sodium oxide, and in the Salicornia lierhacea 2.6 per 
cent of potassium oxide and 36.4 per cent of sodium 
oxide, the sodium oxide constituting in the first instance 
no less than yV '^^^^ i^ the latter ^^ of the entire 
weight, not of the ash, but of the air-dry plant. Potas- 
sium is never absent from these forms of vegetation. 
{Agriculhir-Chemie, 3/e Auf., p. Q(j.) 

According to Cadet {Liehirfs Erndlirung der Veg., 
p. 100), the seeds of the Salsola kali, sown in common 
garden soil, gave a plant which contained both sodium 
and potassium ; from the seeds of this, sown also in 
garden soil, grew plants in which only potassium-salts 
with traces of sodium could be found. These strand- 
])lai]ts are occasionally found at a distance from salt- 
shores, and their growth as strand-plants appears to be 
due to their capacity for flourishing in spite of salt, and 
not from their requiring it. {Hoffmayin, Vs. St., XIJI, 
p. 295.) 



192 HOW CROPS GROW. 

Another class of plants — the sea- weeds {algm) — de- 
rive their nutriment exclusively from the sea-water in 
which they are immersed. Though the quantity of po- 
tassium in sea-water is hut ^^ that of the sodium, it is 
yet a fact, as shown hy the analyses of Forchhammer 
{Jour, fur Prakt. Cltem., 3G, p. 391) and Anderson 
{Trans. High, and Ag. Soc, 1855-7, p. 349) that the 
ash of sea-weeds is, in general, as rich, or even richer, in 
potassium than in sodium. In 14 analyses, by Forch- 
hammer, the average amount of sodium in the dry weed 
was 3.1 per cent; that of potassium 2.5 per cent. In 
Anderson's results the pei'centage of potassium is inva- 
riably higher than that of sodium.* 

Analogy with land-plants would lead to the inference 
that the sodium of the sea-weeds is in a great degree ac- 
cidental. In fact, Fiicus vesicidosis and Zygogonium sal- 
iniiin have been observed to flourish in fresh water. 
{Vs. ^/., XIII, p. 295.) 

Iron is Essential to Plants. — It is abundantly 
proved that a minute quantity of ferric oxide, Fe203, is 
essential to growth, though the agricultural plant may 
be perfect if provided with so little as to be discoverable 
in its ash only by sensitive tests. According to Salm- 
Horstmar, ferrous oxide, FeO, is indispensable to the 
colza plant. {Versticlie, etc., p. 35.) Knop asserts that 
maize, which refuses to grow in entire absence of iron, 
flourishes when ferric phosphate, which is exceedingly 
insoluble, is simply suspended in the solution that bathes 
its roots for the first four weeks only of the growth of 
the plant. {Vs. St., V, p. 101.) 

We find that the quantity of ferric oxide given in the 
analyses of the ashes of agricultural plants is small, being 
usually less than 07ie per cent. 

Here, too, considerable variations are observed. In 



*Doiibtless due to the fact that the material used by Anderson was 
freed hy washing from adhering common salt. 



THE ASH OF PLANTS. 193 

the analyses of the seeds of cereals, ferric oxide ranges 
from an unweighable trace to 2 and even 3%. In root 
crops it has been found as high as 5%. Kekiile found 
ill the ash of gluten from wheat 7.1% of ferric oxide. 
(Jahresberichf tier Oheni., 1851, p. 715.) Schulz-Fleeth 
found 17.5% in the ash of the albumin from the juice of 
the potato tuber. The proportion of a^Ji is, however, so 
small that in case of potato-albumin the ferric oxide 
amounts to but 0.12 per cent of the dry substance. {Der 
Ratio7ielle Ackerhau, p. 82.) 

In the ash of wood, and especially in that of bark, ferric 
oxide often exists to the extent of 5 to 10%. The largest 
percentages have been found in aquatic plants. In the 
ash of the duckweed i^Lemna trisulca) Liebig found 
7.4%. Gorup-Besanez found in the ash of the leaves of 
the Trapa nutans 29.6%, and in the ash of the fruit- 
envelope of the same plant G8.6%. {Ann. Ch. Ph., 118, 
p. 2230 

Probably much of the iron of agricultural and land 
plants is accidental. In case of the Trapa natans, we 
cannot suppose all the iron to be essential, because the 
larger share of it exists in the tissues as a brown powdery 
oxide which nniy be extracted by acids, and has the ap- 
pearance of having accumulated there mechanically. 

Doubtless a portion of the iron encountered in anal- 
yses of agricultural vegetation has never once existed 
within the vegetable tissnes, bnt comes from the soil, 
which adheres with great tenacity to all parts of plants. 

Manganese is Unessential to Agricultural Plants. 
Manganese is commonly much less abundant than iron, 
and is often, if not usually, as good as wanting in agri- 
cultural plants. It generally accompanies iron where 
the latter occurs in considerable quantity. Thus, in the 
ash of Trapa, the oxide Mn304 was found to the extent 
of 7.5-14.7%. Sometimes it is found in mucn larger 
quantity than oxide of iron ; e. g.. G. Fresenius found 
13 



194 HOW CRors grow. 

11.2% of oxide of manganese in ash of leaves of the red 
beech [Fagits sylvatica) that contained but 1% of oxide 
of iron. In the ash of oak leaves (Qucrcus 7'ohur) Neu- 
bauer found, of the former G.G, of the latter but 1.2%. 

In ash of the wood of the larch [Larix Euroijcea), Bot- 
tinger found 13.5% Mn304 and 4.2% FcgOs, and in ash 
of wood of Pinus sylvestris 18.2% Mn304, and 3.5% 
FcqCs. In ash of the seed of colza, Nitzsch found 16.1% 
Mn304, and 5.5 FcaOg. In case of land plants, these 
higli percentages are accidental, and specimens of most 
of the plants just named have been analyzed, which were 
free from all but traces of oxide of manganese. 

Salm-IIorstmar concluded from his experiments that 
oxide of manganese is indispensable to vegetation. 
Sachs, Knop, and most other experimenters in water- 
culture, make no mention of this substance in the mix- 
tures, which in their hands have served for the more or 
less perfect development of a variety of agricultural 
plants. Birncr & Lucanus have demonstrated that man- 
ganese is not needful to the oat-plant, and cannot take 
the place of iron. ( Vs. St., VIII, p. 43.) 

Is Chlorine Indispensable to Crops? — What has 
been written of the occurrence of sodium in plants ap- 
pears to apply in most respects equally well to chlorine. 
In nature, sodium is generally associated with chlorine 
as common salt. It is most probably in this form that 
the two substances usually enter the plant, and in the 
majority of cases, when one of them is })resent in large 
quantity, the other exists in corresponding quantity. 
Less commonly, the chlorine of plants is in combination 
with potassium exclusively. 

Chlorine is doubtless never absent from the perfect 
agricultural plant, as produced under natural conditions, 
though its quantity is liable to great variation, and is 
often very small — so small as to be overlooked, except by 
the careful analyst. In many analyses of grain, chlorine 



THE ASH OF PLANTS. 195 

is not mentioned. Its absence, in many cases, is due, 
without doubt, to the fact that chlorine is readily dissi- 
pated from the ash of substances rich in phosphates or 
silica, on prolono'ed exposure to a higli temperature. In 
some of the later analyses, in which the vegetable sub- 
stance, instead of being at once burned to ashes, at a 
liigli red heat, is first charred at a lieat of low redness, 
and then leached with water, which dissolves the chlo- 
rides, and separates them from the unburned carbon and 
other matters, chlorine is invariably mentioned. In the 
tables of analyses, the averages of chlorine are undeni- 
ably too low. This is especially true of the grains. 

The average of chlorine in the 26 analyses of wheat by 
Way and Ogston, p. 150, is but 0.08%, it not being found 
at all in the ash of 21 samples. In Zoeller's later anal- 
yses chlorine is found in every instance, and averages 
0.7%. In Lawes and Gilbert's numerous analyses of 
wheat-grain ash chlorine ranges from to 1.14%, the 
average being 0.1%. In wheat-straw ash they found 
from 1.08 to 2.0G%. The ash was in all cases prepared 
by burning at a low red heat. 

Like sodium, chlorine is particularly abundant in the 
stems and leaves of those kinds of vegetation which grow 
in soils or other media containing much common salt. It 
accompanies sodium in strand and marine plants, and, in 
general, the content of chlorine of any plant may be large- 
ly increased or diminished by supplying it to or withhold- 
ing it from the roots. 

As to the indispensableness of chlorine, we have some- 
what conflicting data. Salm-Horstmar believed that a 
trace of it is needful to the wheat plant, though many of 
his experiments in reference to this element were unsatis- 
factory to himself. Nobbe and Siegert, who have made 
an elaborate investigation on the nutritive relations of 
chlorine to buckwheat, were led to conclude that while 
the stems and foliage of this plant are able to attain a 



19G HOW CROPS GROW. 

considerable development in the absence of chlorine (tlie 
minute amount in the seed itself excepted), presence of 
cldorine is essential to the perfection of the fruit. 

Leydhecker came to the same conclusions as Xobbe 
and Siegert regarding the indispensableness of cldorine 
to the perfection of bucliwlieat. ( Vs. St., VIII, p. 177.) 

On the other hand, Knop excludes chlorine from the 
list of necessary ingredients of maize, buckwheat, cress, 
and Psamma aienaria, having obtained a maize plant 3 
feet liigh, bearing 4 ripe seeds, harvested 23 '^chlorine- 
free seeds" from 5 buck v/ heat-plants, and raised 40 to 50 
ri])e teeds from more than one cress-plant, all grown 
without chlorine. (Vs. SL, XIII, p. 219.) 

Wagner also obtained, in absence of chlorine, maize- 
plants 40 inches high, of 20 gi-ams dry-weight. One of 
tliese ripened 5 small seeds, of which two were proved 
capable of germination ; butnoneof these plants produced 
any pollen and they were fertilized with pollen from 
garden-plants. (Vs. SL, XIII, pp. 218-222.) 

From a series of experiments in water-culture, Birner 
and Lucanus (Vs. St., VIII, p. IGO) conclude that chlo- 
rine is not indispensable to the oat-plant, and has no spe- 
cific effect on the production of its fruit. Chloride of 
potassium increased the weight of the crop, chloiide of 
sodium gave a larger development of foliage and stem, 
chloride of magnesium was positively deleterious, under 
tlie conditions of their trials. 

Lucanus (Vs. St., VII, pp. 3G3-71) raised clover by 
water-culture without chlorine, the crop (dry) weigh- 
ing in the most successful experim.ents 240 times as much 
as the seed. Addition of chlorine gave no better result. 

Nobbe (Vs. St., VIII, p. 187) has produced normally 
developed vetch and pea plants, but only in solutions 
containing chlorine. Beyer (Vs. St., XI, p. 262) found 
exclusion of chlorine in water-culture to prevent forma- 
tion of seed in case of peas ; the plants, after a month's 



THE ASH OF PLA^JTS. 197 

healthy growth, produced new shoots only at the expense 
of the older leaves. In similar trials oats gave a small 
crop of ripe seeds when chlorine was not supplied. 
When, however, the seeds thus obtained nearly free from 
chlorine were vegetated in a solution destitute of this 
element they failed to produce seed agaiu, though their 
growth and rc2)roduction were normal wdien chlorine 
was furnished them in the nutritive solution. 

In Plate I, X shows the extent to which, in Nobbe's 
cultures, buckwheat developed when vegetating for 3 
months in a solution destitute of chlorine, but otherwise 
fully adapted to nourish plants. 

In view of all the evidence, then, it would appear 
Iirobable that chloiine is needful for the cereals, and 
that v/hen the seed and nutritive media (soil or solution 
and air) are entirely destitute of this element fruit cannot 
be perfected. It is probable that in the cases where 
fruit was produced in supposed absence of chlorine this 
substance in some way gained access to the plants. 

Until further more decisive results are reached, we 
are warranted in adopting, with regard to chlorine as 
related to agricultural plants, the following conclu- 
si<ms, viz. : 

1. Chlorine is never totally absent. 

2. If indispensable, but a minute amount is requisite 
for a very considerable vegetative development. 

3. Some plants, as vetches and peas, require a not in- 
considerable amount of chlorine for full development, 
especially of seed. 

4. The foliage and succulent parts may include a 
large quantity of chlorine that is not indispensable to 
the life of the plant. 

Silica is not indispensable to Plants. — The numer- 
ous analyses vv^e now possess indicate that this substance 
is always present in the ash of all parts of agricultural 
plants, when they groiu in natural soils. 



198 now CROPS grow. 

In the ash of the wood of trees, it usually ranges from 
1-3%, but is often found to the extent of 10-20%, or 
even 30%, especially in the pine. In leaves, it is usually 
more abundant than in stems. The ash of turnip leaves 
contains 3-10% ; of tobacco leaves, 5-18% ; of the oat, 
11-58%. (Arendt, Norton.) In ash of lettuce, 20% ; of 
beech leaves, 26% ; in those of oak, 31% have been 
observed. (Wicke, Henneherg^s Jour., lbG2, p. 150.) 

The bark or cuticle of many plants contains an extra- 
ordinary amount of silica. . The cauto tree of South 
America (IllrteUa silicea) is most remarkable in this 
respect. Its bark is very firm and harsh, and is difficult 
to cut, having the texture of soft sandstone. It yields 
31% of ash, and of this 90% is silica. (Wicke, loc. cit., 
p. 143.) 

Another plant, remarkable for its content of silica, is 
the bamboo. The ash of the rind contains 70%, and in 
the joints of the stem are often found concretions of 
hydrated silica, the so-called Tabashir. 

The ash of the common scouring rush (Equisetum Jiije- 
male) has been found to contain 97.5% of silica. The 
straw of the cereal grains, and the stems and leaves of 
grasses, both belonging to the botanical family Grami- 
nacm, are specially characterized by a large content of 
silica, ranging from 40-70% of the ash. The sedge and 
rush families likewise contain much of this substance. 

The position of silica in the plant would thus appear 
to be, in general, at the surface. Although it is present 
in other parts of the plant, yet the cuticle is usually rich- 
est, especially where the content of silica is large. Davy, 
in 1799, drew attention to the deposition of silica in the 
cuticle of the grasses and cereals, and advanced the idea 
that it serves these plants an office of support similar to 
that enacted in animals by the bones. 

In case of the pine (Pimis sylvestris), AVittstein has 
obtained results which indicate that the age of wood or 



Wood of a 


tr 


ee, 


220 


years 


old, 


32.5% 


(( u 






170 


" 




24.1 


(( <( 






135 


n 




15.1 


Bark 






220 


(( 




30.3 


tt (t 






170 


" 




14.4 



THE ASn OF PLANTS. 190 

bark greatly influences the content of silica. He found 
in ash of the — 



And in- 



" " 135 •' 11.9 

In the ash of the straw of the oat, Arendt found the 
percentage of silica to increase as the plant approached 
maturity. So the leaves of forest trees, which in autumn 
are rich in silica, are nearly destitute of this substance 
in spring time. 

Silica accumulates then, in general, in the older and 
less active parts of the plant, whether these be external 
or internal, and is relatively deficient in the younger and 
really growing portions. This rule is not without excep- 
tions. Thus, the chaff of wheat, rye and oats is richer 
in silica than any other part of these plants, and Bottin- 
ger found the seeds of the pine richer in silica than the 
wood. 

In numerous instances, silica is deposited in or upon 
the cell-wall in such abundance that when the organic 
matters are destroyed by bui'uing, or removed by sol- 
vents, the form of the cell is preserved in a silicious 
skeleton. This has long been known in case of the 
Equisetums and Deutzias. Here the peculiar rough- 
nesses of the stems or leaves are fully incrusted or inter- 
penetrated by silica, and the ashes of the cuticle present 
the same appearance under the microscope as the cuticle 
itself. 

The hairs of nettles, hemp, hops, and other rough- 
leaved plants, are highly silicious. 

According to Wicke, the beech owes the smooth and 
undccayed surface which its trunk presents, to the silica 
of the bark. The best textile materials, which are bast- 



200 HOW CROPS GROW. 

fibers of various plants, viz., common hemp, Manila 
henij) {Musa textilis), aloe-hemp {Agave A7nericana) , 
common flax, and New Zealand flax {Phormium tenax) 
are incrusted with silica. In jute {Corchorns textilit<) 
some cells are partially incrusted. The cotton fiber is 
free from silica. Wicke {loc. cif.) suggests that the du- 
rability of textile fibers is to a degree dependent on their 
content of silica. 

Sachs, in 1862, was the first to publish evidence that 
silica is not a necessary ingredient of maize. He ob- 
tained in his early essays in water-culture a maize plant 
of considerable development, whose ashes contained but 
0.7% of silica. Shortly afterwards, Knop produced a 
maize plant with 140 ripe seeds, and a dry-weight of 50 
grammes (nearly 2 oz. av. ) so free from silica that a 
mere trace of this substance could be found in the root, 
but half a milligramme in the stem, and 22 milligrammes 
in the 15 leaves and sheaths. It was altogether absent 
from the seeds. The ash of the leaves of this i)lant thus 
contained but 0.54 per cent of silica, and the stem but 
0.07 per cent. Way & Ogston had fonnd in the ash of 
field-grown maize, leaf and stem together, 27.08 per 
cent of silica. 

In the numerous experiments that htive been made 
more recently upon the growth of plants in aqueous solu- 
tions, by Sachs, Knop, Nobbe & Siegert, Stohmann, 
Eautenberg & Kilhn, Birner & Lucanus, Leydhecker, 
Wolff, and Hami)e, silica, in nearly all cases, has been 
excluded, so far as it is possible to do so, in the use of 
glass vessels. This has been done without prejudice to 
the development of the plants. Nobbe & Siegert and 
W^olff especially Iktvc succeeded in producing buckwheat, 
maize, and the oat, in full perfection of size and parts, 
with this exclusion of silica. 

Wolff {Vs. St., VIII, p. 200) obtained in the ash of 
maize thus cultivated, 2 to 3% of silica, while the sauie 



THE ASH OF PLANTS. 201 

two varieties from the field contained in tlicir ash 11^ to 
13%. The i)ro|)ortion of ash was essentially the same in 
both cases, viz., about 6%. Wollf's results with the oat 
plant were entirely similar. 

Birner & Lucanus (Vs. St., VIII, p. 141) found that 
the supply of soluble silicates to the oat made its casli very 
rich in silica (40%) bat diminished the growth of straw, 
without affecting that of the seed, as compared with 
phmts nearly destitute of silica. 

It is thus made certain that plants oi'dinarily rich in 
siHca may attain a high devel:)pment in absence of this 
substance. We shall see later, however (p. ), that 
silica is probably not altogether useless to plants when 
they grow under ordinary conditions. 

Jodin reports having bred maize by water-culture, with 
the utmost practicable exclusion of silica, for four gener- 
ations — whereby this substance was reduced to the merest 
traces — without interference with the normal develop- 
ment of the plant. {Ann. Affro?i., IX, p. 385.) 

The Ash-Ingredients, which are Indispensable 
to Crops, may b^ taken up in Larger Quantity than 
is Essential. — More than eighty ye^irs ago, Saussure de- 
scribed a simple experiment which is conclusive on this 
point. Ho gathered a number of peppermint plants, [ind 
in some determined the amount of dry matter, which 
was 40.3 per cent. The roots of others were then im- 
mersed in pure v/atcr, and the ])hints were allowed to veg- 
etate 2^ months in a place exposed to air and light, but 
sheltered from rain. 

At the termination of the experiment, the plants, 
which originally weighed 100, had increased to 216 parts, 
and the dry matter of these plants, which at fii'st was 
40.3, had become 02 parts. The plants could have 
acquired from the glass vessels and pure water no con- 
siderable quantity of mineral matters. It is plain, then, 
that the ash-ingredients vv^hich were contained in two 



202 HOW CROPS GROW. 

parts of the peppermint were sufficient for the produc- 
tion and existence of three parts. We may assume, 
therefore, that at least one-third of the ash of the origi- 
nal i)lants was in excess, and accidental. 

The fact of excessive absorption of essential asli-ingre- 
dients is also demonstrated ])y the precise experiments of 
Wolff on buckwheat, already described (see p. 104), 
where the point in question is incidentally alluded to, 
and the difficulties of deciding how much excess may 
occur, are brought to notice. (See also pp. 192 and 194 
n regard to potassium and iron.) 

As further striking instances of the influence of the 
nourishing medium on the quantity of ash-ingredients in 
the plant, the following are adduced, which may serve to 
put in still stronger light the fact that a plant does not 
always require what it contains. 

Nobbe & Siegert have made a comparative study of 
the composition of buckwheat, grown on the one hand in 
garden soil, and on the other in an aqueous solution of 
saline matters. (The solution contained magnesium 
sulphate, calcium chloride, phosphate and nitrate of 
potassium, with phosphate of iron, which together con- 
stituted 0.310% of the liquid.) The aslNpercentage was 
much higher in the water-plants than in the garden- 
plants, as shown by the subjoined figures. (Vs. St., V, 
p. 132.) 

Per cent of ash in 

iSfems and leaves. Roots. Seeds. Entire plant. 

Water-plant 18.G 15.3 2.G 1G.7 

Garden-plant 8.7 0.8 2.4 7.1 

W^e have seen that well-developed plants contain a 
larger proportion of ash than feeble ones, when they 
grow side by side in the same medium. In disregard of 
this general rule, the water-plant in the present instance 
has an ash-percentage double that of the land-plant, 
although the former was a dwarf compared with the lat- 
ter, yielding but ^ as much dry matter. The seeds, how- 
ever, are scarcely different in composition. 



THE ASH OF PLANTS. 203 

Similar results were obtained by Councler with the 
leaves of Acer negundo (Vs. St., XXIX, p. 242), 1,000 
parts of the perfectly dry leaves contained : 

Water-plant. Soil-plant. 

SiUca, SiOj, 8.51 23.72 

Sulphuric oxide, SO3, 38.97 9.09 

Pliosphoric oxide, PaOr,.- • -26.00 4.5G 

Iron oxide, FesO;,, 1.94 1.22 

Magnesium oxide, MgO,. .. 7.56 0.25 

Calcium oxide, CaO, 31.77 36.17 

Sodium oxide, Na^O, 1.23 0.88 

Potassium oxide, KjO, 96.92 45.05 

212.90 127.54 

Leaves of the water-plant are much richer in ash -ingre- 
dients, especially in sulphate and phosphate of potassium. 
Those of the soil-plant contain more silica and lime. 

Disposition by the Plant of Excessive or Super- 
fluous Ash-ingredients. — The ash-ing-redients taken 
up by a plant in excess beyond its actual wants may be 
disposed of in three ways. The soluble matters — those 
soluble by themselves, and also inca2"»able of forming in- 
soluble combinations with other ingredients of the plant 
— viz., the alkali chlorides, sulphates, carbonates, and 
phosphates, the chlorides of calcium and magnesium, 
may — 

1. Remain dissolved in, and diffused throughout, the 
juices of the plant ; or, 

2. May exude upon the surface as an efflorescence, and 
be washed olf by rains. 

Exudation to the surface has been repeatedly observed 
in case of cucumbers and other kitchen vegetables, grow- 
ing in the garden, as well as Avith buckwheat and bai'ley 
in water-culture. {Vs. St., VI, p. 37.) 

Saussure found in the white incrustations upon cucum- 
ber leaves, besides an organic body insoluble in water and 
alcohol, calcium chloride with a trace of magnesium 
chloride. Tlie organic substance so enveloped the cal- 
cium chloride as to prevent deliquescence of the latter. 
(Reclierclies sur la Ver/., p. 2G5.) 



204 HOW CHOPS GUOW. 

Saussiire proved that foliage readily yields up saline 
matters to water. He placed liazel leaves eight success- 
ive times in renewed portions of pure water, leaving them 
therein 15 minutes each time, and found that by this 
treatment they lost yV of their ash-ingredients. The 
portion thus dissolved was cliiefly alkaline salts ; hut con- 
sisted in part of earthy phosphates, silica, and oxide of 
iron. {Reche relies, p. 287.) 

Eitthausen has shown that clover which lies exposed to 
rain after being cut may lose by washing more than one- 
half of its ash-ingredients. 

^1\\\(\qv {Cliemie dor Ackerhriimc, II, p. 305) attributes 
to loss by rain a considerable share of the variations in 
percentage and composition of the fixed ingredients of 
plants. AV"e must not, however, forget that all the exper- 
iments which indicate great loss in this way have been 
made on the cut plant, and their results may not hold 
good to the same extent for uninjured vegetation. 

3. The insoluble matters, or those which become so in 
the [)lant, viz., the calcium sulphate, the oxalates, phos- 
phates, and carbonates of calcium and magnesium, the 
oxides of iron and manganese, and silica, may be depos- 
ited as crystals or concretions in the cells, or mayincrust 
the cell-walls, and thus be set aside from the sphere of 
vital action. 

In the denser and comparatively juiceless tissues, as in 
bark, old wood, and lipe seeds, we find little variation in 
the amount of soluble matters. These are present in 
large and variable quantity only in the succulent organs. 

In bark (cuticle), wood, and seed envelopes (husks, 
shells, chaff) we often find silica, the oxides of iron 
and manganese, and calcium carbonate — all insoluble 
substances — accumulated in considerable amount. In 
bran, phosphate of magnesium exists in comparatively 
large quantity. In the dense teak wood, concretions of 
calcium phosjihate have been noticed. Of a certain 



THE ASH OF PLANTS. 



205 



species of cactus (Cactus senilis) 80% of the dry 
matter consists of crystals of calcium oxalate and phos- 
phate. 

That the quantity of matters thus segregated is in some 
degree proportionate to the excess of them in the nourish- 
ing medium in which the plant grows has been observed 
by Nf>bbe & Siegert, who remark that the two portions 
of buckwheat, cultivated by them in solutions and in gar- 
den-soil respectively (p. 203), both contained crystals 
and globular crystalline masses, consisting probably of 
calcinm and magnesium oxalates, and phosphates, depos- 
ited in the rind and pith ; but that these were by far most 
abundant in the water-plants whose ash-percentage luas 
twice as great as that of the garden-plants. 

These insoluble substances may be either entirely unes- 
sential, or, having once served the wants of the plant, may 
be rejected as no hmger useful, and by assuming the in- 
soluble form, are removed from the sphere of vital action, 
and become in reality dead matter. They are, in fact, 
excreted, though not, in general, 
formally expelled beyond the limits 
of the plant. They are, to some 
extent, thrown oif into the bark 
or into the older Avood or pith, 
or else are encysted in the living- 
eel Is. 

The occurrence of crystallized salts 
thus segregated in the cells of plants 
is illustrated by the following cuts. 
Fig. 23 represents a crystallized con- 
cretion of calcium oxalate, having a 
cellulose, from a leaf of the Avalnut. 




Fiir 



basis or skeleton of 
(Payen, Chimie In- 
dustrielle, PI. XII, ) Fig. 24 shows a mass of crystals of the 
same salt, from the leaf stem of rhubarb. Fig. 25 illus- 
trates similar crystals from the beet root. In the root of 
the young bean, vSachs found a ring of cells, containing 



20G 



HOW CEOPS GEOW. 




Fig. 24. 



crystals of sulphate of lime. {SitzungslericlLte derWien. 

Akad., 37, p. 106.) Bailey ob- 
served in certain parts of tlie in- 
ner bark of the locust a series of 
cells, each of which contained a 
crystal. In the onion-bulb, and 
many other plants, crystaTs are 
^^' ^' abundant. {Gray^s Botanical 
Text-Booh, Gth ed.. Vol. II, p. 52.) 

Instances are not wanting in which there is an obvious 
excretion of mineral matters, or at least a throwing of 
them off to the surface. Silica, as we have seen, is often 
found in the cuticle, but is usually imbedded in the cell- 
w^all. In certain plants, other substances accumulate in 
considerable quantity without the cuticle. A striking ex- 
ample is furnished hy Saxifraga crustata, i\^ low European 
plant, which is found in lime soils. 
The leaves of this saxifrage are en- 
tirely coated with a scaly incrusta 
tion of calcium and magnesium 
carbonates. At the edges of the 
leaf this incrustation acquires a 
considerable thickness, as is illus- 
trated by figure 20, a. In an anal- 
ysis made by linger, to whom these 
facts are due, the fresh (undried) 
leaves yielded to a dilute acid 
4.14<^ of calcium carbonate, and 
0.82% of magnesium carbonate. 

linger learned by microscopic 
investigation that this excretion 
of carbonates proceeds mostly from a series of granular 
expansions at the margin of the leaf, which are directly 
connected with tlie sap-ducts of the jdant. {Bitzungsbe- 
riclite der Wicn. Ahad., 43, p, 519.) 

In figxiic 2(i, <i represents the appearance of a leaf, iiiayuilied 4| diaiii- 




D 



Fig. 26, 



THE ASn OF PLANTS. 2G7 

eters. Around tlio liordcM-s are seen the scalos of carbonates; some of 
these have been detached, leaving round pits on the surface of the leaf : 
c, d exhibit the scales themselves, e in proiile : b shows a leaf, freed 
from its incrustation by an acid, and from its cuticle by i^otash-solution, 
so as to exhibit the veins (ducts) and glands, whose course the carbon- 
ates chieily take, in their passage through the plant. 

Further as to the state of ash-ingredients. — It is 
by no means true that the ash-ingredients always exist in 
plants in thefurms under which they are otherwise famil- 
iar to us. 

Arendt and Helh-iegel have studied the proportions of 
soluble and insoluble matters, the former in the ripe oat 
plant, and the latter in clover at various stages of growth. 

Arendt extracted from the leaves and stems of the oat 
plant, after thorough grinding, the whole of the soluble 
matters by repeated washings in water.* He found that 
all the sulphuric acid and all the chlorine were soluble. 
Nearly all the phosphoric acid was removed by water. 
The larger share of the calcium, magnesium, sodium and 
potassium compounds was soluble, though portions of each 
escaped solution. Iron was found in both the soluble and. 
insoluble state. In the leaves, iron v/ai fouud among the 
insoluble matters after all phosphoric acid lial been re- 
moved. Finally, silica was mostly insoluble, though in 
all cases a small quantity occurred in the soluble condi- 
tion, viz., 3-8 parts in 10,000 of the dry plant. ( IVach- 
sthum der Haferpflanze, pp. 168, 183-4. See, also, table 
on p. 171). 

Weiss and Wiesner discovered by microchemical in- 
vestigation that iron exists as insoluble ferrous and ferric 
compounds both in the cell-membrane and in the cell- 
contents. {Sitztuvjsherichte der Wiener Alcad.,M), 278.) 

Helli-iegel found that in young clover a larger propor- 
tion of the various bases was soluble than in the mature 
plant. As a rule, the leaves gave most soluble matters, 
the leaf stalks less, and the stems least. He obtained, 



*To extract the soluble i^arts of the grain in this way was imiiossible. 



208 HOW CROPS GROW. 

among others, the following results (Vs. St., IV, 
p. 59) : 

Of 100 parts of the following fixed ingredients of clover, 
were dissolved in tiie sap, and not dissolved — 

In young leaves. Infull-grown leaves. 

Pot '1^1. (dissolved 75.2 37.3 

■^^^'^^'^ I undissolved 24.8 62.7 

J-.. (dissolved G9.5 72 4 

-^""^ \ undissolved 30.5 27.6 

MiLHi esi 1 ' dissolved 43.6 78.3 

iviaj,nesia. . . ^ undissolved 56.4 21.7 

Phosphoric i dissol ved 20.9 19.9 

oxide, PoOg I undissolved 79.1 80.1 

Qiiir.^ ' I dissolved 26-8 16.1 

*^"^'^ luncUssolved 73.2 83.9 

These researches demonsti-ate that potassium and sodi- 
um — hodies, all of whose commonly-occurring compounds, 
silicates excepted, are readily soluble in water — enterinto 
insoluble combinations in the plant ; while phosphoric 
acid, which forms insoluble salts with calcium, magnesi- 
um, and iron, is freely soluble in connection with these 
bases in the sap. 

It should be added that sulphates may be absent from 
the plant or some parts of it, although they are found in 
tlie ashes. Thus, Arendt discovered no sulphates in the 
lower joints of the stem of oats after blossom, though in 
the upper leaves, at tlie same period, sulpluiric oxide 
(SO3) formed nearly ?% of the sum of tlie fixed ingre- 
dients. [Wachsthum der Haferpf., ^. 157.) Ulbricht 
found that sulphates were totally absent from the lower 
leaves and stems of red clover, at a time when they were 
present in the upper leaves and blossom. ( Vs. St. , IV. , p. 
30 Tab 'lie. ) Both Arendt and Ulbricht observed that sul- 
phur existed in all parts of the plants they experimented 
upon ; in the parts just specified, it was, however, no 
longer combined to oxygen, but had, doubtless, become 
an integral part of s^me albuminoid orotlier complex or- 
ganic body. Thus the oat stem, at the period above cited, 
contained a qiantity of sulphur, Avhich, had it been con- 
verted into sulphuric oxide, would have amounted to 14% 



THE ASn OF PLAITTS. 209 

of the fixed ingredients. In the clover leaf, at a time 
when it was totally destitnte of snlphates, there existed 
an amount of sulphur which, in the form of sulphuric 
oxide, would have made 13.7% of the fixed ingredients, 
or one per cent of the dry leaf itself.* 

Other ash-ingredients. — Salm-Horstmarhas describ- 
ed some experiments, from which he infers that a minute 
amount of Lithium and Fluorine (the latter as fluoride 
of potassium) are indispensable to the fruiting of barley. 
(Jour, far prakt. Chem., 84. p. 140.) The same observer, 
some years ago, was led to conclude that a trace of Titan- 
ium is a necessary ingredient of plants. The later re- 
sults of water-culture would appear to demonstrate that 
tliese conclusions are erroneous. 

The rare alkali-metal, BuMdium, has been found in the 
sugar-beet, in tobacco, coffee, tea, and the grape. It doubt- 
less occurs, perhaps together with the similar Caesium in 
many other plants, though always in very minute quan- 
tity. Birner and Lucanus found that these bodies, in the 
absence of potassium, acted as poisons to the oat. {Vs, 
St., VIII, p. 147.) 

According to Nol)be, Schroeder and Erdmann, Litli- 
i7im is very injurious to buckwdieat, even in presence of 
potassium. When lithium was substituted for two- 
thirds of the potassium of a normal nutritive solution, 
buckwheat vegetated indeed for 3 months, the stem 
reaching a length of 18 inches, but the plant w\as small 
and unhealthy, the leaves were pale and the older ones 
dropped away, as shown by VIII, plate I. ( Vs. St., 
XIII, p. 35G). 

* Arencltv^n,?, the first to estimate sulphuric oxide (SO3) in vegetable 
matters with accuracy, and to discriminate it from the sulphur of or- 
tranic compounds. Tliis chemist separated the sulpliates of the oat- 
plant by extracting the pulverized material with acidulated water. He 
likewise estimated the total sulphur by a special metliod, and by sub- 
tracting the sidphur of the sulphuric oxide from the total lie obtained as 
a difference that portion of sulphur which belonged to tlie alliuminoids, 
etc. In his analysis of clover, Ulhricfif followed a similar plan. ( J"s. St., 
in, p. 147.) As has already been stated, many of the older analyses are 
wholly untrustworthy as regards suliihvirand sulphuric oxide. 

14 



210 now CROPS GROW. 

The investigations of A. Braun and of Eisse (SachSp 
Exj:). Physiologie, 153) show that Zi7ic is a usual ingredi- 
ent of plaiits gi'owing about zinc-mines, where the soil 
contains carbonate or silicate of this metal. Certain 
marked varieties of plants are peculiar to, and appear to 
have been jn-oduced by, such soils, viz., a violet {Viola, 
tricolor, var. calaminaris), and a shepherd's purse 
(Tlila^iyi alpestre, var. calaminaris). In the ash of the 
leaves of the latter plant, Risse found 13% of oxide of 
zinc ; in other plants he found from 0.3 to 3.3%. Theso 
plants, however, grow equally well in absence of zinc, 
which may slightly modify their appearance, but is unes- 
sential to their nutrition. 

Boron as boric acid has recently been found in many 
wines of California and Europe. 

Copjicr is often or commonly found in the ashes of 
plants; and other elements, viz.. Arsenic, Barium and 
Lead, have been discovered therein, but as yet we are not 
warranted in assuming that any of these substances are 
of importance to agricultural vegetation. The soluble 
compounds of copper, arsenic and lead are in fact very 
injurious to plant life, unless very highly diluted. 

Iodine, an invariable and probably a necessary constit- 
uent of many algae, is not known to exist to any consid- 
erable extent or to be essential in any cultivated plants. 

§4. 

FUKCTIONS OF THE ASH-INGREDIENTS. 

Although much has been written, little is certainly 
known, with reference to the subject of this section. 

Sulphates. — The albuminoids, which contain sulphur 
as an essential ingredient, obviously cannot be produced 
in absence of sulphates, which, so far as we know, are the 
exclusive source of sulphur to plants. The sulphurized 



THE AST! OF PLANTS. 211 

oils of the onion, mustard, horse-radish, turnip, etc., like- 
wise require sulphates for their organization. 

Phosphates. — 'J'he j)hosphorized substances (prota- 
gon, lecUhin, diloropliyl) require to their elaboration that 
phosphates be at the disposal of the plant. Knophas shown 
that hypophosphites cannot take the place of phosphates. 
The albuminoids which are probably formed in the foliage 
must pass thence through the cells and ducts of the stem 
into growing parts of the j^lant, and into the seed, where 
they accumulate in large quantity. But the albuminoids 
penetrate membranes with great difficulty and slowness 
when in the pure state. The di- and tri-2:)otassic phosphates 
dissolve or form water-soluble compounds with many 
albuminoids, and, according to Schumacher {Physik der 
Pflanze, p. 128), considerably increase the diffusive rate 
of these bodies, and thus facilitate their translocation in 
the plant. 

Potassium. — The organic acids, viz., oxalic, malic, 
tartaric, citric, etc., require potassium to form the salts 
of this metal, which exist abundantly in plants, e. g. , 
potassium oxalate in sorrel, potassium bitartrate in the 
grape, potassium malate in garden rhubarb; and without 
potassium it is in most cases probably impossible for the 
acids to accumulate or to be formed. Mercadante culti- 
vated sorrel (Oxalis acetosella and Riimex acetosa), m ab- 
sence of potassium-salts; sodium, calcium, andmagnesiam 
being supplied. The plants failed to fructify, and their 
juices contained but one-eighth as much free acid (or acid 
salts?) as exists in the sap of the same kind of plants veg- 
etating under normal conditions. The acids — oxalic, with 
a little tartaric — were united to calcium (Bericlite, 1875, 
II, p. 1200). The organic acids may result from the de- 
composition of carbhydrates (starch or sugar), or they 
may be preliminary stages in the production of the carb- 
hydrates. In either case their formation is an index to 
the constructive processes by which the plant originates 



212 now CROPS grow. 

new vegetable substance and increases in dry weigbto 
Mercadante's observations aretberefore in accord witli tbe 
results of tbe investigations next to be considered. 

In 18G9, Nobbe, Scbroder, and Erdinann employed tbe 
method of water-culture to make an elaborate stud}' of 
tbe influence of potassium on the vegetative processes, 
and found tbat, all other needful conditions of growtli 
being supplied, in absence of potassium buckwheat 
plants vegetated for three months without any increase in 
v/eight — that is to say, without })roducing new vegetable 
matter. Examination of these miniature plants demon- 
strated that (in absence of potassium) the first evident 
stage in the production of vegetable substance, viz., tlie 
appearance of starch in tlie cldorophyl grcmiiles of the 
leaf, could not be attained. The experimenters therefore 
drew the conclusion that potassium is an essential factor 
in the assimilation of carbon and the formation of starch. 
They found that the plants were able to produce starch 
when potassium was supplied either as .chloride, nitrate, 
phosphate or sulphate. The transfer of the starch from 
the leaves to the fruit, or its conversion into a soluble 
form, appeared to require the presence of chlorine ; ac- 
cordingly, potassium chloride gave the best developed 
plants, especially at the period of fructification. This 
conclusion was greatly strengthened by the observation, 
repeatedly made, that the miniature ])lants which had 
vegetated for three or four weeks without increase of 
weight, or growth other than that which the seedling can 
make at the expense of the seed, began at once, on suit- 
able addition of potassium chloride to the nutritive solu- 
tion, to form starch, discoverable in all the cblorophyl 
granules, and thenceforward developed new stems and 
leaves and grew in quite the normal manner. In Plate 
I the appearance of some of the plants produced in these 
trials is shown. la represents the average plant raised 
in the normal solution containing abundance of potas- 




PLATE I. 

EXPLANATION. (See p. 212.) 

Water-cultiires of Japanese Buckwheat, supplied with the inerre 
dieiits of a Normal Solution, viz. : Siilphates, Nitrates, I'hospliates and 
Chlorides of Potassivim, Magnesium, Calcium and Iron, except as staled 
helow. 

I and la. Solution normal. Potassium as Chloride. 

II. Solution without Totassium. 

II3. Without Potassium for 4 weeks, thereafter Potassium Chloride. 

III. Potassium as Nitrate. Chlorine as in Normal. 

IV. Potassium as Sulphate. Chlorine one-fourth of Normal. 

V. Potassium as Phosphate. Chlorine one-fifth of Normal. 

VI. Sodium but not Potassium. 

VIII. Lithium. 

IX. Without Calcium. 

X. W^ithout Chlorine. 

XI. Without Nitrogen. 

The meter-scale (39| inches) serves to measure the dimensions of tlie 
plants. 




— iv.+Cot. +K.+Cot. — K.— Cot. +K.— Cot. 

c. a. d. b. 

PLATE II. 

EXPLANATION. (See p. 213.) 
Water-ciiltures of Flower' ng Bean after vegetating 38 days. 

a. In normal solution, seed with cotyledons. 

b. In normal solution, seed without cotyledons. 

c. In potassium-free solution, seed with cotyledons. 

d. Ill potassium-free solution, seed without cotyledons. 



THE ASH OF pla:n'ts. 213 

siiim chloride. II was deprived of potassium save that 
contained in the seed. In IV and V, respectively, the 
chlorine of the solution was reduced to one-fourth and 
one-fifth the amounts contained in the normal solution 
and replaced by sulphuric acid in IV and by phosplioric 
acid in V. hi case of II3, tlie plant vegetated without 
potassium for four weeks with a result similar to IL and 
then for two months was supplied with potassium cjiIo- 
ride. For numerous interesting- details reference must 
be made to the original paper ( Vs. St., XIII, pp. 
321-424). 

Liipke, from water-cultures with the flowering bean 
Phiiseoliis muUijiorus, and common bean P. vidgaris, 
lias recently arrived at different conclusions. He finds 
that these plants are able, under the utmost possible ex- 
clusion of potassium, to assimilate carbon and produce 
starch, in fact to grow and to carry on all the vegetative 
functions that belong to the fully-nourished plant, 
though on a diminished scale. In order to limit the 
supply of potassium to the utm;)st, the cotyledons of some 
of the plants were cut away when the plumule began to 
apj^ear above them. In this way 90% of the potassium 
of the seed was removed* and while the plants were 
thereby reduced in dimensions, their power to vegetate 
in a healthy manner was not suppressed. After 65 days 
of vegetation one of these plants yielded a crop of dry- 
substanco 4.8 times as much as was contained in the 
newly spnmted seedling after excision of the cotyledons. 

Some results of these cultures are shown in Plate II. 
The stem of the unmutilated flowerinor bean in normal 
solution I, a, reached a final length of 80 inches, that de- 
prived of potassium grew to 40 ii^-ches. 

Mobbe's conclusion that potassium is specifically essen- 
tial or concerned in starch-production is accordingly erro- 

* Lii]ik(' f(van(l that ono seed of P. m^iJfifJnrus contained 23 miUisranis 
of potassium oxide; tlie seedUug, after cutting olf the cotyledons, con- 
tains 2.3 mm. 



214 now CROPS grow. 

neons. As Liipke remarks, potassium is rather like nitro- 
gen, pliosphorus, sulphur, etc., one of the elements of 
which probably a cercain quantity is indispensable to the 
formation of every vegetable cell. Nobbe's results per- 
haps indicate that buckwheat requires relatively more 
potassium than the bean for its processes of growth. 
[Land. JaliriilJier, JSS^, pp. 887-913.) 

Calcium. — Bohm {Jahreshericht ilher Ag, Chemie, 
1875-G, Bd. I, p. 255) and Von Raumer ( Vs. St., XXIX, 
251) have furnished evidence that calcium (lime) is di- 
rectly necessary to the formation of cell-tissue, that is to 
say, of cellulose. 

This evidence rests upon observations made with seed- 
lings of the flowering bean (scarlet-runner), Fhaseolus 
?nuUifiorns. When a seed sprouts, the young plant at first 
is nourished exclusively by the nutritive matters contained 
in the seed. When its roots enter the soil it begins to de- 
rive water, nitrogen, and ash-ingredients from the earth. 
When its leaves unfold in the light it begins to gatlier 
c;irl)on from the air and to increase in weight. If its 
roots are placed in pure water it can acquire no ash-in- 
gredients ; if its leaves are kept in darkness it can gain 
nothing from the air. Thus circumstanced, it may live 
and vegetate for a time, but constantly loses in total dry 
weight, and its apparent growth is only the formation of 
new parts at the expense of the old. For-sofhe days the 
youuGf stem shoots upward without green color, but per- 
fectly formed, and then (in case of the flowering bean) 
•suddenly, at a little space below the terminal bud, a dis- 
coloration appears, the stem wilts, withers, and dies 
away. The growth of stem that thus occurs is accom- 
panied by and depends upon the solution of starch in the 
seed-lobes and its transfer to the points of growth where 
it is made over into cellulose — the frame-work of the 
stem. In absence of any external source of ash-ingredi- 
ents the young' stem dies long before the starch of the 




THE ASH OF PLANTS. 215 

cotyledons is consumed. But if the roots be placed in 
a nutritive solution suited to water-culture, the stem 
grows on without injury until the cotyledons are com- 
pletely emptied of starch, and afterwards continues to de- 
velop at the expense of the loAver leaves. 

Tiie arrest of growth in the stem evidently is due to 
the absence of some one or more ash-ingredients, and 
Bohm found in fact that, by withholding lime-salts from 
the roots, this characteristic malady was invariably pro- 
duced. Hence he concludes that calcium compounds are 
immediately concerned in the conversion of starch into 
cellulose. 

Magnesium. — Von Raumer,in the paper just referred 
to {Vs. St., XXIX, pp. 263 and 273), gives his observa- 
tions on the relations of the magnesium salts to the veg- 
etative processes. He states that, all other conditions 
being favorable, the exclusion of magnesium from a nu- 
tritive solution in which the scarlet-runner vegetates is , 
folloAved by cessation of chloropliyl-production and of S '^z 
that enlargement of the new-formed cells wherein the \ 
act of growth largely consists. Accordingly, in absence 
of magnesium-supply, the plants, which at first grew nor- 
mally, after reaching a height of forty inches, began to 
show signs of disturbed nutrition. The uppermost in- 
ternodes (joints) of the stems almost ceased to lengthen 
and became exceptionally thick and hard, their leaves 
failed to open, and both joints and leaves were white in 
color with but the faintest tint of green. Soon new up- 
ward growth ceased altogether, the terminal bud and 
unfolded leaves dried away, and, while the lower, first- 
formed and green leaves remained fresh for weeks and 
the lower stem threw out new shoots, healthy growth 
was at a stand-still, and the plants gradually witliered 
and perished. The normal growth of the bean plants 
for a month or more in nutritive solutions containing no 
magnesium is accounted for by the supply of this ele- 



216 HOW CROPS GROW. 

ment existin:^ in the seed,* which evidently was enough 
for the necessities of growth until the stem was forty 
inches high. From that point on the plants almost 
ceased to grow, and gradually died from want of food 
and inability to assimilate. 

We have already seen that, according to Hoppe-Seylery 
magnesium is a constant and presumably an essential in- 
gredient of chlorophyilan, a crystallized derivative of 
chlorophyl. This makes evident that magnesium is di- 
rectly concerned in and needful to the formation of the 
chlorophyl granules which, so far as observation as yet 
has gone, are the seat of those operations which first 
construct organic substance from inorganic matter. 

Magnesium and calcium occur in the aleurone of seeds 
and, according to Griibler, form soluble, crystallizable 
compounds with certain albuminoids, so that these ele- 
ments, like potassium, may be concerned in the transport 
of protein-bodies. 

Silica. — Humphrey Davy was the first to suggest that 
the function of silica might be, in case of the grasses, 
sedges, and equisetums, to give rigidity to the slender 
stems of these plants, and enable them to sustain the 
often heavy weight of the fruit. 

The results of the many experiments in water-culture 
by Sachs, Knop, AVoltf, and others (see p. 200), in which 
the supply of silica has been reduced to an extremely 
small amount, without detriment to the development of 
plants, commonly rich in this substance, prove in the 
most conclusive manner, however, that silica does not 
essentially contribute to the stiffness of the stem. 

Wolff distinctly informs us that the maize anil oat 
plants produced by him, in solutions nearly free from 
silica, were as firm in stalk, and as little inclined to 
lodge or *May," as those which grew in the field. 



* Common beans contain abont one-fonrth of one per cent of mag' 
nesia. 



THE ASH OF PLANTS. 21? 

The " lodging" of cereal crops is demonstrated to re- 
sult from too close a stand and too little light, which 
occasion a slender and delicate growth, and is not per- 
ceptibly influenced by presence or absence of silica. 
Silica, liowever, if not necessary to the life of the cereals, 
appears to have an important office in their perfect de- 
velopment under ordinary circumstances. Kreuzhage 
and Wolff have carefully studied the relations of silica to 
the oat plant, nsing the method of water-culture. In a 
series of nine trials in 1880, where, other things being 
equal, much silica, little silica, and no silica were sup- 
plied, the numbers of seeds produced were l,4;i3, 1,039, 
and 715 respectively, the corresponding weights being 
46, 34, and 23 grams. Tlie total crops weighed l.<6, 
172, and 1G8 grams respectively, so that while tlie yield 
of seed was doubled in presence of abundant silica, the 
total crop (dry) was increased in weight but one-sixth. 
The supply of silica was accompanied with an absolutely 
diminished root-formation as well as by a relatively in- 
creased seed-production. Similar trials in 1881 and 1882 
gave like results {Vs. SL, XXX, p. 161). Wolff con- 
cludes that silica ensures the timely and uniform ripen- 
ing of the crop as well as favors the maximum develop- 
ment of seed. 

The natural supply of silica appears to be always suf- ^ 
ficient. Application of this substaiice JJi- fertilizers lias ■' 
never proved remunerative. In those water-cultures 
where large seed-production has been ol)tained in ab- 
sence of silica, it is probable that lime-salts, phospliates, 
or other ash-ingredients, which are commonly taken up 
more abundantly than in field culture, have brought 
about the same result that silica usually effects. This 
action of the ash-ingredients is apparently due to a clog- 
ging of the cell-tissues and consequent check of the pro- 
cesses of growth and would seem to be caused either by 
the otherwise unessential silica or by an excess of the 



218 UOW CKOPS GKOW. 

inf,n-edients essential to gTowth. The hard, dense coat of 
the seed of the common weed '^stone-crop" (Lithos^jer- 
niiim) nsually contains some 13 to 20 per cent of silica 
and twice that amonnt of calcium carbonate. Ilohnel 
produced these seeds in water-culture from well-grown 
2)Iants deprived of silica and found them quite normally 
developed. The seed-coat was permeated with calcium 
carbonate, wdiich appears to have fully replaced silica 
without detriment to the plant (UaberlantU, Unter- 
sitchungcn, II, p. 160). 

Chlorine. — As has been mentioned, both Nobbe and 
Leydhecker found that buckwheat grew quite well up to 
the time of blossom without chlorides. From that 
period on, in absence of chlorides, remarkable anomalies 
ap})eured in the development of the plant. In the ordi- 
nary course of growth, starch, which is organized in the 
mature leaves, does not remain in them to much extent, 
but is transferred to the newer organs, and especially to 
the fruit, where it often accumulates in large quantities. 
In absence of chlorides in the experiments of Nobbe and 
Leydhecker, the terminal leaves becam. thick and fleshy, 
from extraordinary development of cell-tissue, at the 
same time they curled together and finally fell off, upon 
slight disturbance. The stem became knotty, transpira- 
tion of water was suppressed, the blossoms withered 
without fructification, and the plant prematurely died. 
Tlie fleshy leaves were full of starch-grains, and it aj)- 
peared that in absence of chlorine the transfer of starch 
from the foliage to the flower and fruit was rendered im- 
])ossible ; in other words, chlorine (in combination with 
potassium or calcium) was concluded to be necessary to 
—was, in fact, the agent of — this transfer. 

Knop believes, however, that these phenomena are due 
to some other cause, and that chlorine is not essential to 
the perfection of the fruit of buckwheat (see p. 196). 
Kno]) {Cliem. Centralblatt, 1869, p. 189) obtained some 



\ 



THE ASH OF PLANTS. 219 

ri])e, well-developed buckwheat seeds in chlorine-free 
water-cultures, while in the same solutions, with addition 
of chlorides, other buckwheat plants remained sterile, 
the flowers withering without setting seed. Knop states 
that in other trials maize and bean plants grew better 
without than with chlorides. In either case starch did 
not accumulate in the stem or leaves of maize, while all 
the organs of the bean were overloaded with starch both 
in presence and absence of chlorides. 

The experiments of Nobbe and Leydhecker are very 
circumstantially described and have been confirmed by 
the later work of Nobbe, Schroder, and Erdmann ( Vs, 
SL, XIII, pp. 302-G). See p. 196. 

Iron. — We are in possession of some interesting facts, 
which throw light upon the function of this metal in the 
plant. In case of the deficiency of iron, foliage loses its 
natural green color, and becomes pale or white even in 
the full sunshine. In absence of iron a plant may un- 
fold its buds at the expense of already organized matters, 
as a potato-sprout lengthens in a dark cellar, or in the 
manner of fungi and white vegetable parasites ; but the 
leaves thus developed are incapable of assimilating carbon, 
and actual growth or increase of total weight is impossi- 
ble. Sahn-IIorstmar sliowed (1849) that plants which 
grow in soils or media destitute of iron are very pale in 
color, and that addition of iron-salts very sj^eedily gives 
tliem a healthy green. Sachs found that maize-seed- 
lings, vegetating in solutions free from iron, had their 
first three or four leaves green ; several following were 
white at the base, the tips being green, and afterward 
perfectly white leaves unfolded. On adding a few drops 
of sulphate or chloride of iron to the nourishing medium, 
the foliage was plainly altered witliin twenty-four hours, 
and in three to four days the plant acquired a deep, lively 
green. Being afterwards transferred to a solution desti- 
tute of iron, perfectly white leaves were again developed. 



220 HOW CKOPS GROW. 

and these were bronglit to a normal color by addition of 
iron. 

E. Gris was the first to trace the reason of these effects, 
and first found (in 1843) that watering the roots of 
plants with solutions of iron, or applying such solutions 
externally to the leaves, shortly developed a green color 
where it was previously wanting. By microscopic stud- 
ies he found that, in the absence of iron, the protoplasm 
of the leaf-cells remains a colorless or yellow mass, desti- 
tute of visible organization. Under the influence of iron, 
grains of cliloroplujl begin at once to aj^pear, and pass 
through the various stages of normal development. We 
know that the power of the leaf to decompose carbon 
dioxide and assimilate carbon resides in the cells that 
contain chlorophyl, or, we may say, in the chlorophyl- 
grains themselves. We understand at once, then, that 
in the absence of iron, whicli is essential to the forma- 
tion of chlorophyl, there can be no proper growth, no 
increase at tlie expense of the external atmospheric food 
of vegetation. 

Risse, nndor Sachs's direction {Exp. Pliysiologic, p. 
143), demonstrated that ?7?a?i(/a;2ese cannot take the placo 
of iron in the office just described. 



CHAPTER III. 

§ 1. 

QUAKTITATIYE RELATIONS AMONG THE INGREDIENTS 

OF PLANTS. 

Various attempts have been made to exhibit definite 
numerical relations between certain different ingredients 
of plants. 

Equivalent Replacement of Bases. — In 1840, Lie- 
big, in his Chemistry (qj^jUecl to Agriculture, suggested 



QUANTITATIVE RELATIONS. 221 

that the various bases or basic metals might disj)lace 
each other in equivalent quantities, i. e., in the ratio of 
their molecular or atomic weights, and that, were such 
the case, the discrepancies to be observed among analyses 
should disappear, if the latter were interpreted on this 
view. Liebig instanced two analyses of the ashes of fir- 
wood and two of pine-wood made by Berthier and Saus- 
sure, as illustrations of the correctness of this theory. 
In the fir of Mont Breven, carbonate of magnesium was 
present ; in that of Mont La Salle, it was absent. In 
the former existed but half as much carbonate of potas- 
sium as in the latter. In both, however, the same total 
percentage of carbonates was found, and the amount of 
oxygen in the bases was the same in both instances. 

Since the unlike but equivalent quantities of potash, 
lime, and magnesia contain the same quantity of 0x3^- 
gen, these oxides, in the case in question, really replaced 
each other in equivalent projiortions. The same was 
true for the ash of j^ine-woocl, from Allevard and from 
Norway. On applying this pi'inciple to other cases it 
has, however, signally failed. The fact that the plant 
can contain accidental or unessential ingredients ren- 
ders it obvious that, however truly euch a law as that of 
Liebig may in any case apply to those substances which 
are really concerned in the vital actions, it will be impos- 
sible to read the law in the results of anal3'ses. 

Relation of Phosphates to Albuminoids. — Liebig 
likewise considered that a definite relation exists be- 
tween the phosphoric acid and the albuminoids of the 
ripe grains. That this relation is not constant is evi- 
dent from the following statement of data bearing on 
the question. In the table, the amount of nitrogen (N), 
representing the albuminoids (see p. 113), found in vari- 
ous analyses of rye and wheat grain, is compared with 
that of phosphoric acid (P2O5), the latter being taken as 
vinity. The ratios of P2O5 to N were found to range as 
follows : 



222 HOW CROPS GROW. 



P.O.. N, 



In 7 Samples of Rye-kernel by Fehllng & Faiszt. . - 1 : 1.97—3.00 

•• 11 " " '• Mayer 1 : 2.04—2.38 

" 5 •' '• " Bibra 1 : 1.G8— 2.81 

«« 6 " " " Siegert.. 1:2.35—2.96 

«« 28 '* " " the extreme range was from — 1:1.68—3.06 

" 2 " " Wheat-kernel by Fehling & Faiszt 1 : 2.71— 2.8G 

•' 11 " " " Mayer 1:1.83—2.19 

«« 2 «» " " Zoeller 1:2.02—2.16 

•• 30 " " " Bibra 1:1.87—3.55 

*• G " " " Siegert 1 : 2.30—3.33 

" 51 " " '* the extreme range Avas from — 1:1.83—3.55 

Siegert, who collected these data {Vs. St.j III, p. 147), 
and who experimented on the itilluence of phosphatic and 
nitrogenous fertilizers upon the composition of wheat and 
rye, gives ns the general result of his special inquiries that 
FhospJwric acid and Nitrofjen stand in no cunsiant rela- 
lion to each other. Nitrogenous manures increase the per 
cent of nitrofjen and diminish that of phosphoric acid. 

Other Relations. — All attempts to trace simple and 
constant rehitious between other ingredients of plants, 
viz., between starch and alkalies, cellulose and silica, etc., 
have proved fruitless. 

It is much rather demonstrated that the proportion of 
the constituents is constantly changing from day to day as 
the relative mass of the individual organs themselves un- 
dergoes perpetual variation. 

In adopting the above conclusions it is not asserted that 
such genetic relations between phosphates and albumin- 
oids, or between starch and alkalies, as Liebig first sug- 
gested and as various observers have labored to show, do 
not exist, but simply that they do not ai^jDear from the 
analyses of plants. 

§2. 

THE COMPOSITION- OF THF: PLANT IN SUCCESSIVE STAGES 

OF GROWTH. 

We have hitherto regarded the composition of the plant 
mostly in a relative acnse, and have instituted no conipar- 



COMPOSITION IN SUCCESSIVE STAGES. 223 

isoTis between the absolute quantities of its ingredients at 
different stages of growth. We liave obtained a series of 
isolated views of the chemistry of the entire plant, or of 
its parts at some certain period of its life, or when placed 
under certain conditions, and have thus sought to ascer- 
tain the peculiarities of these periods, and to estimate the 
influence of these conditions. It now remains to attempt 
in some degree the combination of these sketches into a 
panoramic picture — to give an idea of the comjDosition 
of the plant at the successive steps of its devel')pme7it. 
We shall thus gain some insight into the rate and manner 
of itG growth, and acquire data that have an important 
bearing on the requisites for its perfect nutrition. For 
this purpose we need to study not only the relative 
(percentage) composition of the plant and of its parts at 
various stages of its existence, but we must also infoi'm 
ourselves as to the total quantities of each ingredient at 
these periods. 

We shall select from the data at hand those which 
illustrate the composition of the oat-plant. Not only the 
ash -ingredients, but also the organic constituents, will be 
noticed so far as our information and space permit. 

The Composition and Growth of the Oat-Plant 
may be studied as a type of an important class of agricul- 
tural i^lants, viz.: the annual cereals — plants which com- 
plete their existence in one summer, and which yield a 
large quantity of nutritious seeds — the most Valuable re- 
sult of culture. The oat-plant was first studied in its 
various parts and at different times of development by 
Prof. John Pitkin Norton, of Yale College. His labori- 
ous research published in 1846 (Trans. Highland and Ag. 
8oc., 1845-7, also J??2. Jour. ofSci. a?id Arts.Yol. 3, 1847) 
was the first step in advance of the single and disconnected 
analyses which had previously been the only data of the 
agricultural physiologist. For several reasons, however, 
the work of Norton was imperfect. The analytic meth- 



224: HOW CROPS GROW. 

ods employed by him, though the best in use at that day, 
aiid handled by him with great skill, were not adapted to 
furnish results trustworthy in all particulars. Fourteen 
years later, Arendt* at Moeckern, and Bretschneiderf at 
Saarau, in Germany, at the same time, but inde^^endently 
of each other, resumed the subject, and to their labors 
the subjoined figures andconchisions are due. 

Here follows a statement of the Periods at which the 
plants were taken for analysis : 

[stiU closed. 

. -p ,. , ) June 18, Arendt— Three loAver leaves unfolded, two upper 
1st I'erioa ^ ^ p^^ liretschneider — Four to five leaves developed, 
o , 1, • 1 I June 30, (12 (lavs), Arendt— Shortly before full heading. 
za 1 eiuKi j^ ,, .^,,^ ^j^) days), Brelsehneider— Tlie plants were headed. 
Qi i:> • 1 I July 10, (10 days), Arendt— Imniediatelv after bloom. 
aa 1 erioti ^ u ^^ ( 9 days), Bretsehneider— Full bh)om. 
dfn T'^virvi I J"ly 21, (11 days), Arendt— Beo-innins to ripen. 
4thleiioa| ,, 2S, (20 days), Bretselmeider— " 
r,th Povio.l l-^^^y ^'' (10 (liiysX Arendt— FuUy ripe. 
o\,n r-ciioti j ^^j^ g^ ^ y days), Bretsehneider- Fully ripe. 

It Avill be seen tliat the periods, though differing some- 
what as to time, correspond almost perfectly in regard to 
the development of the plants. It must be mentioned 
tliat Arendt carefully selected luxiiriaut plants of equal 
size, so as to analyze a uniform material (see p. 171), 
and took no account of the yield of a given surface of soil. 
Bretsehneider, on the other liand, examined the entire 
produce of a square rod. The former procedure is best 
adapted to study the composition of the well-nourished 
individual plant; the latter gives a truer view of the cj^op. 

The unlike character of the material as just indicated 
is but one of the various causes which might render the 
tw^o series of observations discrepant. Thus, diiferences 
in soil, weather and seeding, would necessarily influence 
the relative as well as the absolute development of the two 
crops. The results are, notwithstanding, strikingly ac- 
cordant in many particulars. In all cases the roots were 
not and could not be included in the investigation, as it 
is impossible to free them from adhering soil. 



* Das Wachsfhwn flor Hdforpflftnzo, Loipzia, 1859. 

^Wachsthnnisvcrlialtnlssc del' Ilaferpflanze, Jour.fiir Prakt. Chem.,7&, 
11)3. 



COMPOSITION" IN SUCCESSIVE STAGES. 225 

The Total Weight of Crop per English acre, at the 
end of each period, was as follows: 

Table l.—BrcUchneider. 
1st Period, 6,358 lbs. avoirdixiiois. 
2*1 " 10,G03 " " 

3(1 " 16,G23 " " 

4th " 14,981 " " 

5tll " 10,022 " « 

The Total Weights of Water and Dry Matter for 

all but the 2d Period — the material of which was acci- 
dentally lost — were: 

Table II. — Bretschneider. 

Dry Matter, Water, 

lbs. av. per acre. lbs. av. per acre. 

1st Period, 1,284 5,074 

2d&3d" 4,383 12,240 

4tli " 5,427 9,554 

5tli " 6,886 3,736 

1. — From Table I it is seen: That the weight of the 
live crop is greatest at or before the time of blossom.* 
After this period the total weight diminishes as it had 
previously increased. 

2. — From Table II it becomes manifest: That the organ- 
ic tissue (dry matter) continually increases in quantity up 
to the maturity of the plant; and 

3. — The loss after the 3d Period falls exclusively upon 
the water of vegetation. At the time of blossom the 
plant has its greatest absolute quantity of water, while 
its least absolute quantity of this ingredient is found when 
it is fully ripe. 

By taking the difference between the weights of any 
two Periods, we obtain: 

The Increase or Loss of Dry Matter and Water 
during each Period. 

Table 111.— Bretschneider. 

Dry Matter, Water, 

lbs per acre. lbs per acre. 
1st Period, (58 days), 1,284 Gain. 5,074 Gain. 

2d«&;3d" (10 days), 3,009 " 7,1C6 " 

4tli " (20 days), 1,044 " 2,C86 Loss. 

5th " ( 9 days), 1,459 " 5,818 " 



*In Arendt's Experiment, at tlie time of "heading out," 3d Period. 
15 



22G now CROPS grow. 

On dividing the above quantities by the number of days 
of the respective periods, there results: 

The Average Daily Gain or Loss per Acre during 
each Period. 







TABLE IV. 


—Bretschneicler. 










Dry 


Matter. 




Water. 


1st 


re 


■riod, 


22 lbs. Gain. 


87 


lbs. 


Gain. 


2d & 3d 


K 


163 


a (t 


377 


u 


" 


4tli 




(( 


52 


(( (( 


134 


(( 


Loss. 


5th 




(( 


1G2 


(( (( 


64G 


(( 


u 



4. — Table III, and especially Table IV, show that the 
gain of organic matter in Bretschneider's oat-crop went 
on most rapidly at or before the time of blossom (accord- 
ing to Arendt at the time of heading out). This was, then, 
the period of most active growth. Afterward the rate of 
growth diminished by more than one-half, and at a later 
period increased again, though not to the maximum. 

Absolute Quantities of Carbon, Hydrogen, Oxy- 
gen, Nitrogen (Organic Matter), and Ash in the dry 
oat-crop at the conclusion of the several periods {lbs. 
2Jer acre) : 



/ 


TABLE V. 


—Bretschneicler. 








Carbon. 


Hydrogen. 


Oxygen. 


Nitrogen. 


Jsh.* 


lp,t roriod, 


593 




80 


455 


46 


110 


2d & 3d " 


2,137 




286 


1,575 


122 


263 


41 h 


2,600 




343 


2,043 


150 


2D1, 


.':th 


3,229 




405 


2,713 


1G7 


372 



Amounts of Carbon, Hydrogen, Oxygen, Nitro- 
gen, and Ash-ingredients assimilated by tlie oat-crop 
during the several periods. Water of vegetation is not 
included (Ihs. 2>Gr ocre) : 

Table VI. — Bretschneider. 





Carbon. 


Tlydrofien. 


Oxyfien. 


Nitrogen, 


Ash irrircdients. 


1st Period, 


593 


80 


455 


46 


110 


2d&3d " 


1,.544 


206 


1,575 


76. 


153 


4th 


453 


57 


468 


28 


28 


5th 


629 


62 


670 


17 


81 



*ln P.rotschncidor's analyses, "ash" sicjnifies the residue left after 
carefnlly hiirnins the plant. In Arendt's investiiration the si\lpliur 
and chlorine were determined in the unlnxrned i)lant. 



COMPOSTTTON IN" SUCCESSIVE STAGES. 227 

Relative Quantities of Carbon, Hydrogen, Oxy- 
gen, Nitrogen (Organic Matter) and Ash in the dry 
oat-crop, cit the end of the S3vend periods (per cent) : 

Table yil.—nretschneider. 





Cjrhon. 


Ilijdro'jen . 


Ojyfjen. 


N.troiien. 


( Oifjanic Matter.) 


Ash. 


Ist rei'iod, 


46.22 


G.23 


35.39 


3.59 


91.43 


8.57 


2(1 & 3d " 


48.7(5 


(5.53 


35.1yG 


2.79 


94.04 


5.96 


4t,h " 


47.91 


G.33 


37.G5 


2.78 


94.C7 


5.33 


5th " 


4C.89 


5.88 


39.40 


2.43 


94.60 


5.40 



Relative Quantities of Carbon, Hydrogen, Oxy- 
gen, and Nitrogen, in dry substance, after deducting 
the somewhat variable amount of ash {per cent) : 

Table YIIL—Jircfschneider. 





Carbon. 


Hydrogen. 


Oxygen. 


Nitrogen, 


1st Period, 


50.55 


6.81 


38.71 


3.93 


2d & 3d " 


51.85 


6:95 


38.24 


2.86 


4th 


50.55 


6.96 


30.83 


2.93 


5th 


49.59 


6.21 


41.64 


2.56 



5. The Tables V, VI, VII, and VIII, demonstrate tliat 
while the absolute quantities of the elements of the dry 
oat-plant continually increase to the time of ripening, 
they do not increase in the same proportion. In other 
words, the plant requires, so to speak, a change of diet 
as it advances in growth. They further show tliat nitro- 
gen and ash are relatively more abundant in the young 
than in the mature plant ; in other words, the rate of 
assimilation of Nitrogen and fixed ingredients falls be- 
hind that of Carbon, Hydrogen, and Oxygen. Still oth- 
erwise expressed, the plant as it approaches maturity 
organizes relatively more carbhydrates and less albu- 
minoids. 

The relations just indicated appear more plninly when 
we compiire tlie QnantUies of Nitrogen, ILjdrogen, and 
Oxygen^ assimilated diiriiig each period, calculated ui)on 
the amount of Carbon assimilated in the same time and 
assumed at 100. 

Table IX.—BretscJineider. 

Carbon. Nitrogen. Ili.drogen. Oxygen. 

1st Period, 100 7.8 13.4 73.6 

2d & .3d " 100 4.9 13.3 72.5 

4th " 100 6.1 12.3 100.8 

5th " 100 2.6 10.6 106.5 



228 HOW CROPS GROW. 

From Table IX we see that the ratio of Hydrogen to 
Carbon regularly diminishes as the plant matures ; that 
of Nitrogen falls greatly from the infancy of the plant to 
the period of full bloom, then strikingly increases during 
the first stages of ripening, but falls off at last to mini- 
mum. The ratio of Oxygen to Carbon is the same during 
the 1st, 2d, and 3d Periods, but increases remarkably 
from the time of full blossom until the plant is ripe. 

As already stated, the largest absolute assimilation of 
all ingredients — most rapid growth — takes place at the 
time of heading out, or blossom. At this period all the 
volatile elements are assimilated at a nearly equal rate, 
and at a rate similar to that at which the fixed matters 
(ash) are absorbed. In the first period Nitrogen and 
Ash ; in the 4th Period, Nitrogen and Oxygen ; in the 
5fch Period, Oxygen and Ash are assimilated in largest 
proportion. 

This is made evident by calculating for each period the 
relative average daily increase of each ingredient, the 
amount of the ingredients in the ripe plant being assumed 
at 100, as a point of comparison. The figures resulting 
from such a calculation are given in 





Table 


X.—Bretsc/i 


neider. 








Carbon. 


Ilt/drorjen. 


ryrjen. 


Nitrogen. 


Axh. 


1st Period, 


0.31 


0.33 


0.28 


0.47 


0.50 


2d and 3d " 


2.51 


2.G8 


2.17 


2.39 


2.13 


4th " 


0.89 


0.88 


1.07 


1.06 


0.47 


5th " 


1.49 


1.16 


1.89 


0.75 


1.70 



The increased assimilation of the 5th oyer the 4th 
Period is, in all probability, only apparent. The results 
of analysis, as before mentioned, refer only to those parts 
of the plant that are above ground. The activity of the 
foliage in gathering food from the atmosphere is doubt- 
less greatly diminished before the plant ripens, as evi- 
denced by the leaves turning yellow and losing water of 
vegetation. The increase of weight in the plant above 
ground probably proceeds from matters previously stored 



COMPOSITION Il>r SUCCESSIVE STAGES. 229 

in the roots, which now are tninsf erred to the fruit and 
foliage, and maintain the growth of these parts after 
their power of assimilating inorganic food (CO2, H2O, 
NH3, N2O,) is lost. 

The following statement exhibits the ahsolute average 
daily increase of Carbon^ Hydrogen, Oxygen, Nitrogen, and 
Ash, during the several periods {lbs. 'per acre) : 





TABLE 


XI.—Bretschne, 


Ider. 








Ca''hon. 


Ili/lr >r/en. 





.cijjen. 


Nitrogen. 


Ash. 


1st Period, 


10.0 


1.4 




"7.8 


0.8 


1.9 


2cland3cl " 


81.0 


10.8 




83.0 


4.0 


8.0 


4th " 


22.G 


2.9 




23.4 


1.4 


1.4 


5th " 


70.0 


6.9 




74.4 


1.9 


9.0 



Turning now to Arendt's results, which are carried 
more into detail than those of Bretschneidor, we will 
notice: 

A. — The Relative {percentage) Composition of the 
Entire Plant and of its Parts* during the several 
periods of vegetation. 

1. Fiber \ is found in greatest proportion — 40 per cent 
— in the lower joints of the stem, and from the time 
when the grain ^^ heads out," to the period of bloom. 
Eelatively considered, there occur great variations in the 
same part of the plant at different stages of growth. 
Thus, in the ear, which contains the least fiber, the 
quantity of this substance regularly diminishes, not 
absolutely, but only relatively, as the plant becomes 
older, sinking from 27 per cent at heading to 12 per 
cent at maturity. In the leaves, which, as regards 
fiber, stand intermediate between the stem and ear, this 

* Arenrlt selected large and well-developed plants, divided them into 
six parts, and analyzed eacli part separately. His divisions of the 
plants were: 1, the three lowest joints of tlie stem: 2, the two middle 
joints; 3, the upper joint; 4, the tliree lowest leaves; 5, the two npper 
leaves; 6, the ear. Tlie stems were cut just above tlie nodes, the leaves 
included the sheaths, the ears were stripped from the stem. Arendt 
rejected all plants which were not perfect when gathered. AVhen 
nearly ripe, the cereals, as is well known, often lose one or more of 
their lower leaves. For the numerous analyses on which these conclu- 
sions are based we nuist refer to the original. 

tl. e., Crude cellulose; see p. 45. 



230 now oPvOPS grow, 

siibstanco ranges from 22 to 38 per cent. Prcyious to 
blossom^ the upper leaves, afterwards the lower leaves, 
are the richest in fiber. In the lower leaves the maxi- 
mum (33 per cent) is found in the fourth ; in the upper 
leaves (38 per cent), in the second period. 

The apparent diminution in amount of fiber is due in 
all cases to increased prodiiction of other ingredients. 

2. Fat and Wax are least abundant in tlie stem. Their 
proportion increases, in general, in the upper parts of the 
stem as well as during the latter stages of its growth. The 
range is from 0.2 to 3 per cent. In the ear the propor- 
tion increases from 2 to 3.7 per cent. In the leaves the 
quantity is much larger and is mostly wax with little fat. 
The smallest proportion is 4.8 per cent, which is found in 
tlie upper leaves when the plant is ripe. The largest 
proportion, 10 per cent, exists in the lower leaves, at the 
time of blossom. The relative quantities found in the 
leaves undergo considerable variation from one stage of 
growth to another. 

3. Non-nitrofjenous matters^ other than fiber ^ viz., starch, 
sugars, gums, etc.,* undergo great and irregular variation. 
In the stem the largest percentage (57 per cent) is found 
in the young lower joints; the smallest (43 per cent) in 
ripe upper straw. Only in the ear occurs a regular in- 
crease, viz , from 54 to 63 per cent. 

4. The albuminoidii,\ in Arendt's investigation, exhibit 
a somewhat different relation to the vegetable substance 
from what was observed by Bretschneider, as seen from 
the subjoined comparison of the percentages found at 
the different periods : 

PERIODS. 

I. II. III. IV. V. 

Arendt 20.93 11.G5 10.8G 13.67 14.30 

Bretsclmeider 22.73 17.G7 17.01 15.39 



* What: remains after deducting fat and wax, albuminoids, fiber and 
ash, from tlie dry substance, is here included, 
t Calculated by multiplying the percentage of nitrogen by 0.33. 

These differences may be variously accounted for. They 



COMPOSITION" IK SUCCESSIVE STAGES. 



231 



are due, in part, to the fact that Arondt analyzed only 
large and perfect plants. Bretschneider, on the other 
liand, examined all the plants of a given plot, large and 
small, perfect and injured. The differences illustrate 
what has been already insisted on, viz., that the develop- 
ment of the plant is greatly modified by the circum- 
stances of its growth, not only in reference to its exter- 
nal figure, but also as regards its chemical composition. 

The relative distrihiition of nitrogen in the parts of the 
plant at the end of the several periods is exhibited by the 
following table, simple inspection of which shows the 
llucfcuations (relative) in the content of this element. The 
j)ercentages are arranged for each period separately, pro- 
ceeding from the highest to the lowest : 



PERIODS. 



I. 


II. 


III. 


IV. 


V. 


Upper leaves. 


Lower leaves. 


Upper leaves. 


Ears. 


Ears. 


3.74 


2.3'J 


2.27 


2.85 


3.04 


Lower leaves. 


Upper leaves. 


Lower leaves. 


Upper leaves. 


Upi>er leaves. 


3.38 


2.19 


2.18 


1.1)1 


1.74 


Lower leaves. 


Ears. 


Ears. 


Lower leaves. 


Upper stem. 


2.15 


2.0G 


1.85 


1.G2 


1..^6 




Middle stem. 


Upper stem. 


Ux^per stem. 


Lower leaves. 




1.52 


1.34 


l.GO 


1.43 




Upper stem. 


Middle stem. 


Middle stem. 


Middle stem. 




0.87 


0.98 


1.20 


1.17 




Lower stem. 


Lower stem. 


Lower stem. 


Lower stem. 




0.80 


0.88 


0.83 


0.79 



5. Ash.- — I'he agreement of the percentages of ash in 
the entire plant, in corresponding periods of the growth 
of the oat, in tlie independent examinations of Bret- 
schneider and Arendt, is remarkably close, as appears 
from the figures below : 

PERIODS. 

L XL III. IV. 

Bretschiieider 8.57 5.96 5.33 

Arendt 8.03 5.24 5.44 5.20 



V. 

5.40 
5.17 



As regards the several parts of tlie plant, it was found 
by Arendt that, of the stem, the upper portion was richest 
in ash throughout the whole period of growth. Of the 
leaves, on the contrary, the lower contained most fixed 
matters. In the eat there occurred a continual decrease 



232 HOW CKOPS GROW. 

from its first appearance to its maturity, while in the 
stem and leaves there was, in general, a progressive 
inerease t(nvards the time of ripening. 'J'he greatest 
percentage (10.5 per cent) was fonnd in the ripe leaves; 
the smallest (0.78 per cent) in the ripe lower straw. 

Far more interestins; and instructive than the relative 
proportions are 

B. — The Absolute Quantities of the Ingredients 
found in the Plant at the conclusion of the sev- 
eral periods of growth. — These abs.)hite quantities, 
as found by Arendt, in a given number of carefully- 
selected and vigorous plants, do not accord with those 
obtained by Bretschneider from a given area of ground, 
nor could it be expected that they should, because it is 
next to impossible to cause the same amount of vegeta- 
tion to develop on a number of distinct plots. 

Though the results of Bretschneider more nearly rep- 
resent the crop as obtained in farming, those of Arendt 
give a truer idea of the plant when situated in the best 
possible conditions, and attaining a uniformly high 
development. We shall not attempt to compare the two 
sets of observations, since, strictly speaking, in most 
points they do not admit of comparison. 

From a knowledge of the absolute quantities of the 
substances contained in the plant at the ends of the several 
periods, we may at once estimate the rate of growth, i. c., 
the rapidity ivith ivhich the constituents of the plant are 
either taken np or organized. 

The accompanying table, which gives in alternate col- 
umns the total 2veights of 1,000 p)lants at the end of the 
several periods, and (by subtracting the first from the 
second, the second from the third, etc.) the gain from 
matters absorbed or produced during each period, will 
serve to justify the deductions that follow, which are 
taken from the treatise of Arendt, and which apply, of 
course, only to the plants examined by this investigator. 



COMPOSITION IN SUCCESSIVE STAGES. 



'od 






Hi 

H 
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O 

t— I 
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o 
o 
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X5 
Pi 
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tX) 


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Loss 

Loss 

97.4 

34.2 




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CO o 'w r^ 

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111 &c. 
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P5 






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Los 
14 

325 
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feti<0<j o 






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234 HOW CROPS GROW. 

1. The plant increases in total tceight (dry matter) 
through all its growth, but to unequal degrees in differ- 
ent periods. The greatest growth occurs at the time of 
heading out ; the slowest, within ten days of maturity. 

We may add that the increase of the oat after blossom 
takes place mostly in the seed, the other organs gaining 
but little. The lower leaves almost cease to grow after 
the 2d Period. 

2. Fiber is produced most largely at the time of head- 
ing out (2d Period). When the plant has llnished blos- 
soming (end of 3d Period), the formation of fiber 
entirely ceases. Afterward there appears to occur a 
slight diminution of this substance, more probably due 
to unavoidable loss of lower leaves than to a resorption 
or metamorphosis in the plant. 

3. Fat is formed most largely at the time of blossom. 
It ceases to be produced some weeks before ripening. 

4. Albuminoids are very irregular in their formation. 
The greatest amount is organized during the 4tii Period 
(after blossoming). The gain in albuminoids within 
tliis period is two-Iifths of the total amount found in the 
ripe plant, and also is nearly two-fifths of the entire gain 
of organic substance in the aame period. The absolute 
amount organized in the 1st Period is not much less 
than in the 4th, but in the 2d, 3d and 5tli Periods the 
quantities are considerably smaller. 

Bretsclmeider gives the data for comparing the pro- 
duction of albuminoids in the oat crop examined by him 
with Arcndt's results. Taking the quantity found at 
the conclusion of the 1st Period as 100, the amounts 
gained during the subsequent periods are related as 
follovv's: 

rr.RTops. 

I. IT. III. (II. & III.) IV. (II., III. & IV.) V. 

ArciKlt 100 G7 4G (11.3) 120 (233) 36 

Drctschucider .100 ? ? (1G5) G2 (227) 35 

We perceive striking differences in the comparison. In 



COMPOSITION IK bUCCESSiVE STAGES. 2oi} 

Brctsclineidor's crop tlic increase of jilbuminoids goes on 
most riipidly in the 2d and 3d PeriodSj and sinks nipidly 
during the time when in Arendt's plants it attained the 
maximum. Curiously enough, the gain in the 2d, 3d 
and 4th Periods, taken together, is in both cases as good 
as identical (233 and 227), and the gain during the last 
period is also equal. This coincidence is doubtless, how- 
ever, merely accidental. Comparisons with other crops 
of oats examined, though much less completely, by 
StOckhardt [Chemischer Ackersmann, 1855) and Wolff 
{Die ErsclwpfiuHj des Bodens darch die Cultur, 185G) 
demonstrate that the rate of assimilation is not related 
to any special times or periods of development, but 
de})0]ids upon the stores of food accessible to the plant 
and the favor of the weather, or other external conditions. 

The following figures, which exhibit for each period 
of both crops a comparison of the gain in albuminoids 
with the increase of the other organic matters, further 
strikingly demonstrate that, in the act of organization, 
the nitrogenous principles have no close quantitative 
relations to the non-nitrogenous bodies (carbhydrates 
and fats). 

The quantities of albuminoids gained during each 
period being represented by 10, the amounts of carbhy- 
drates, etc., are seen from the subjoined ratios : 

PEKIODS. 

liafiit in 
I. II & III. IV. V. L'ipe I'lant. 

Aroudt 10 : ;;4 10:114 10:28 10: 25 10 : (iO 

Bret.scliMei(k'r..lO : M 10 : 50 10 : 4(3 10 : 120 10 : 51 

5. The Ash- ingredients of the oat are absorbed through- 
out its entire growth, but in regularly diminishing quan- 
tity. The gain during the 1st Period being taken at 10, 
that in the 2d Period is 9, in the 3d, 8, in the 4:th, 5i, 
in the 5th, 2 nearly. 

The ratios of gain in ash-ingredients to that in entire 
dry substance, are as follows, ash -ingredients being 
assumed as 1, in the successive periods : 



238 HOW CROPS GROW. 

1 : 12i, 1 : 27, 1 : IG, 1 : 23, 1 : 1». 

Accordingly, the absorption of us h -ingredients is not 
proportional to the growth of the plant, but is to some 
degree accidental, and independent of the wants of 
vegetation. 

Recaplt Illation. — Assuming the quantity of each proxi- 
mate element in the ripe plant as 100, it contained at 
the end of the several periods tiie following amounts 
{per cent) : 

Fat. Caibh'jfl rates.* Albuminoids. Ash. 

20 15 27 29 

50 47 45 55 

85 70 57 79 

100 92 90 95 

100 100 100 100 

Taking the total gain as 100, the gain during each 
period was accordingly as follov/s (percent): 

Fiber. Fat. Carbhjidrates.* Albunrinoids. Ash. 







Fiber. 


I. 


reriocl, 


18 


II. 


>t 


81 


III. 


n 


100 


IV. 


it 


loa 


V. 


n 


103 



I. Period, 


18 


20 


15 


27 


29 


II. 


63 


30 


32 


18 


26 


III. 


19 


35 


23 


12 


24 


IV. 





15 


22 


33 


16 


V. 








8 


10 


5 



100 100 100 100 100 

6. — As regards tlie individual ingredients of the ash^ 
the plant contained at the end of each period tlio follow- 
ing amounts, — the total quantity in the ripe ])lant being 
taken at 100. Corresponding results from Brets(jhneider 
enclosed in ( ) are given for comparison: 

Siilpli uric Phosphoric 

Silica. O.ride O.tide Lime. Ma'jnesia. Potash. 

Percent. Percent. Percent. Percent. Percent. Percent. 

I. Period, 18 ( 22) 20 ( 42) 23 ( 23) 30 ( 31) 24 ( 31) 39 ( 42) 

"• " ^'' \ ( 57) •'^2 j ( 44) 42 } ^ 58 j. 42 [ .3 70 j 

II I. «» 70 J 52 1 73 t 79 ) 58 > 91 i 

IV. " 93 ( 72) CO ( 39) 91 ( 74) 99 ( 74) 84 ( 77) 100 (100) 

V, " 100 (100) 100 (100) 100 (100) 100 (100) 100 (100) 100 (VI5*) 

The gain (or loss, indicated by the minus sign — ) in 
these ash-ingredients during each period is given below: 



* Exclusive of Fiber. 



COMPOSITION^ IN SUCCESSIVE STA.GES. 237 

Sulphuric Phosphoric 







Silica. 


OdiUe. 


Oxide. 


Lime. 


Magnesia. 


Potash. 






Per cent. 


. Per cent. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


I. 


Period 


, 18 ( 22) 


20 ( 42 ) 


23 ( 23) 


30 ( 31 ) 


24 ( 31) 


39 ( 42 ) 


II. 
III. 


(( 

a 


2^ [ ( 35) 

21) i 


-}(., 


JJ!(40, 


^«}(52) 


l'}(42) 
16* ^ 


^11' «) 


IV. 


(( 


23 ( 15) 


38 (—5*) 


18 ( 10) 


20 (—9*) 


2G ( 4 ) 


9 ( 11 ) 


V. 


i( 


7 ( 28) 
100 (100) 


10 ( 56 ) 
100 (100) 


9 ( 27) 
100 (100) 


1 ( 17 ) 
100 (100) 


IG (23 ) 
100 (100) 


(-5*) 




100 (100) 



These two independent investigations could hardly 
give all the discordant results observed on comparing 
the above figures, as tlie simple consequence of the 
unlike mode of conducting them. We observe, for 
example, that in the last period Arendt's plants gathered 
less silica than in any other — only 7 per cent of the 
whole. On the other hand, Bretschneider's crop gained 
more silica in this than in any other single period, viz. : 
28 per cent. A similar statement is true of pliosphoriG 
oxide. \ It is obvious that Bretschneider's crop was tak- 
ing up fixed matters much more vigorously in its last 
stages of growth than were Arendt's plants. As to 
potash, we observe that its accumulation ceased in the 
4th Period in both cases. 

C. — Translocation of Substances in the Plant. 
■ — The transfer of certain matters from one part of tlie 
plant to another during its growth is revealed by the 
analyses of Arendt, and since such changes are of inter- 
est from a physiological point of view, we may recount 
them here briefly. 

It has been mentioned already that the growth of tlic 

stem, leaves, and enr of the oat plant in its later stages 

' probably takes place to a great degree at the expense of 

the roots. It is also probable that a transfer of carblifj- 



*In these Instances Bretsclnieider's later crops appear to contain less 
sulphuric oxide, lime and potash, tlian the earlier. This result maybe 
due to the wasliing of tlie crop by rains, but is probably caused by 
unequal development of the several plots. 

• tPlin^Phoric oxide is the "phosphoric acid," PgOn, of okler and to a 
great degree of current usage. See p. 163. 



'ZoS ' now ciiors gkow. 

drates, and certain tluit one of alhuminoids, goes on from 
the leaves tlirouoli the stem into the ear. 

/Silica appears not to be subject to any change of posi- 
tion after it has once been fixed by the plant. CJdorlne 
likewise reveals no noticeable mobility. 

On the other hand, phosphoric oxide passes rapidly from 
the leaves and stem towards or into the fruit in the ear- 
lier as well as in the later stages of growth, as shown by 
the folloAving figures : 

One thousand plants contained in the various periods 
quantities (gi'ams) of phosphoric oxide as follows : 





\st 


2d 


M 


Ath 


5th 




Period. 


Pet iod. 


Period. 


Pei iod. 


Period. 


3 lower joints of stem, 0.47 


0.20 


0.21 


0.20 


0.19 


2 middle " 


(( 


0.39 


1.14 


0.46 


0.18 


Upper joint 


(i 


O.OG 


1.73 


0.31 


0.39 


3 lower leaves 


«' 1.05 


0.70 


0.69 


0.51 


0.35 


2 upper leaves 


" 1.75 


1.67 


1.18 


0.74 


0.59 


Ear, 




2.36 


5.36 


10.67 


12.52 



Observe that these absolute quantities diminish in the 
stem and leaves after the 1st or 3d Period in all cases, 
and increase very rapidly in the ear. 

Arendt found that sidphuric oxide existed to a much 
greater degree in the leaves than in the stem through- 
out the entire growth of the oat plant, and that, after 
blossoming, the lower stem no longer contained suli)hur 
y in the form of sulphates at all, though its total in the 
plant considerably increased. It is almost certain, then, 
that sulphuric oxide orif/iinUes, eitlier parliaJly or wholly, 
by oxidation of sulphur or some su]})hurized compound, 
in tlie u]>|)er organs of the oat. 
/ Mu'jiii'sinm is translated from t]ie lower stem into the 
^j upper organs, and in the fruit, especially, it constantly 
( increases in quantity. 

There is no evidence that Calcium moves upward in 
the plant. On the contrary, Arendt's analyses go to 
show that in the ear, during the last period of growth, it 



COMPOSITION IK SUCCESSIVE STAGES. 239 

diminishes in quantity, being, perhaps, replaced by 
magnesium. 

As to potassium, no transfer is fairly indicated, except 

^•^i . from the ears. These. contained at blossoming (Period 

'XJ^ 111) a maximum of potassium. During their subsequent 

growth the amount of this element diminished, being 

probably displaced by magnesium. 

The data furnished by Arendt's analyses, while they 
indicate a transfer of matters in the cases jnst named, 
and in most of tliem with great certainty, do not and 
cannot from their nature disprove the fact of other simi- 
hir changes, and cannot fix the real limits of i\\Q move- 
ments Avliicli they point out. 



DIVISION II. 

THE STEUCTURE OF THE PLANT AND 
OEEICES OF ITS ORGANS. 

CHAPTER I. 

GENERALITIES. 

"We have given a brief description of those elements 
and compounds which constitute the plant in a chemical 
sense. They are the materials — the stones and timbers, 
so to speak — out of which the vegetable edifice is built. 
It is important, in the next place, to learn how these 
building materials are put together, what positions they 
occupy, wdiat purposes they serve, and on what plan 
the edifice is constructed. 

It is impossible for the builder to do his work until he 
has mastered the plans and specifications of the archi- 
tect. So it is hardly possible for the farmer with cer- 
tainty to contribute in any great, especially in any new, 
degree, to the upbuilding of the plant, unless he is 
acquainted with the mode of its structure and the ele- 
ments that form it. It is the happy province of science 
to add to the vague and general information which the 
observation and experience of generations have taught, 
a more definite and particular knowledge, — a knowledge 
acquired by study purposely and carefully directed to 
special ends. 

An acquaintance with the parts and structure of the 
plant is indispensable for understanding the mode by 
which it derives its food from external sources, while the 
16 241 



212 now cRors grow. 

ingenious methods of propagation practiced in fruit- and 
flower-culture are only intelligible by the help of this 
knowledge. 

Organism of the Plant. — We have at the outset 
spoken of organic matter, of organs and organizatiouo 
It is in the world of life that these terms have their fit= 
test application. The vegetable and animal consist of 
numerous parts, differing greatly from each other, but 
each essential to the whole. The root, stem, leaf, flower 
and seed are each instruments or or gems whose co-oper- 
ation is needful to the perfection of the plant. The 
plant (or animal) being thus an assemblage of organs, is 
called au Organism; it is an Organized or Organic 
Structure. The atmosphere, the waters, the rocks and 
soils of the earth, do not possess distinct co-operating 
parts ; they are Biorga7iic matter. 

In inorganic nature, chemical affinity rules over the 
transformations of matter. A plant or animal that is 
dead, under ordinary circumstances, soon loses its form 
and characters ; it is gradually consumed, and, at the ex- 
pense of atmospheric oxygen, is virtually burned up to 
air and ashes. 

In the organic world a something, which we call 
Vitality, resists and overcomes or modifies the affinities 
of oxygen, and insures the existence of a continuous and 
perpetual succession of living forms. 

An Organism or Organized Structure is characterized 
and distinguished from inorganic matter by two par- 
ticulars : 

1. It builds up and increases its own mass by appro- 
priating external matter. It absorbs and assimilates 
food. It grows by the enlargement of all its parts. 

2. It reproduces itself. It develops from a germ, and 
in turn gives origin to new germs. 

Ultimate and Complex Organs. — In our account 
of the Structure of the Plant we shall first consider the 



ELEMEIN'TR OF OKGAXTZED STRUCTURE. 243 

elements of that stnicturc — the Cells — which cannot he 
divided or wounded without extinguishing their life, 
and by whose expansion or multiplication all growth 
takes place. Then will follow an account of the com- 
plex parts of the lAiiut — its Organs — which are built up 
by the juxtaposition of numerous cells. Of these we 
have one class, viz., the Roots, Stems and Leaves, whose 
office is to sustain and nourish the Individual Plant. 
These may be distinguished as the Vegetative Organs. 
The other class, comprising the Flower and Fruit, arc 
not essential to the existence of the individual, but their 
function is to maintain the Race, They are the Er2iro- 
ductive Organs. 

CHAPTER 11. 
PRIMARY ELEMENTS OF ORGANIZED STRUCTURE. 

§ 1. 

THE VEGETABLE CELL. 

One of the most interesting discoveries that the micro- 
scope has revealed, is that all organized matter originates 
in the form of minute vesicles or cells. If we examine 
by the microscope a seed or an egg, we find nothing but 
a cell-structure — a mass of rounded or many-sided bags 
lying closely together, and more or less filled with solid 
or liquid matters. From these cells, then, comes the 
frame or structure of the plant or of the animal. In the 
process of maturing, the original vesicles are vastly mul- 
tiplied and often greatly modified in sliape and appear- 
ance, to suit various purposes ; but still it is always easy, 
especially in the plant, to find cells of the same essential 
characters as those occurrinc: in the seed. 



2U 



now CROPS GROW. 



Cellular Plants. — In the simpler forms or lower 
orders * of vegetation, we find plants which, throughout 
all the stages of their life, consist entirely of similar 
cells, and indeed, many are known which are but a single 
cell. The phenomenon of red snow, frequently observed 
in Alpine and Arctic regions, is due to a microscopic 
one-celled plant which propagates with great rapidity, 
and gives its color to the surface of the snow. In the 
chemist's laboratory it is often observed that in tlie clear- 
est solutions of salts, like the sulphates of sodium and 
magnesium, a flocculent mold, sometimes red, some- 
times green, most often white, is formed, which, under 
the microscope, is seen to be a vegetation consisting of 
single cells. Brewers' yeast. Fig. 27, is nothing more 
than a mass of one or few-celled plants. 

In sea-weeds, mushrooms, the molds that grow on 
damp walls, or upon bread, cheese, etc., and in the 
blights whicli infest many of the farmer's cmp^, we have 
examples of plants formed exclusively of cells. 





Fi":. 37. 



Fls: 28. 



All the plants of higher orders we find likewise to 
consist chiefly of globular or angular cells. All the 
growing parts especially, as the tips of the roots, the 
leaves, flowers and fruit, are, for the most part, aggrega- 
tions of such minute vesicles. 

If we exc'imine the pulp of fruits, as that of a ripe 

*Viz. : the Cn/ptofranift, inolndiiis Molds and Mushrooms (Fuiiffi), 
Mosses, Ferns, Sea-Weeds (Alyce) and Bacteria {Schizomycetes). 



ELEMEITTS OF ORGANIZED STRUCTURE. 






apple or tomjito, we are able, by means of a low magni- 
fier, to distinguish the cells of which it almost entirely 
consists. Fig. 28 represents a bit of the flesh of a ripe 
pipi)in, magnilied 50 diameters. The cells mostly cohere 
together, but readily admit of separation. 

Structure of the Cell. — By the aid of the micro- 
scope it is 230ssible to learn something with regard to the 
internal structure of the cell itself. Fig. 29 exhibits the 
ajopcarance of a cell from the flesh of the Artichoke 
(Helicmthus), magnified 230 diameters ; externally the 
membrane, or wall of the cell, is seen in section. This 
membrane is filled and distended by a 
transparent liquid, the sap or free water 
of vegetation. Within the cell is ob- 
-& served a round body, b, which is called 
the nucleus, and uj^on this is seen a 
smaller nucleohis, c. Lining the inte- 
rior of the cell-membrane and connected 
with the nucleus, is a yellowish, turbid, 
semi-fluid substance of mucilaginous 
consistence, a, which is designated the protoplasm, or 
formafive layer. This, when more highly magnified, is 
found to contain a vast number of excessively minute 
granules. 

By the aid of chemistry the microscopist is able to dis- 
sect these cells, which are hardly perceptible to the 
unassisted eye, and ascertain to a good degree how they 
are constituted. On moistening them with solution of 
iodine, and afterward with sulphuric acid, the outer 
membrane — the cell-ivall — shortly becomes of a fine blue 
color. It is accordingly cellulose, the only vegetable 
substance yet known which is made blue by iodine after, 
and only after, the action of sulphuric acid. At the 
same time we observe that the interior, half-liquid, pro- 
toplasm, coagulates and shrinks together, — separates, 
therefore, from the cell-wall, and, including with it the 




240 now CKors grow. 

nucleus and the smaller grannies, lies in the center of 
the cell like a collapsed bladder. It also assumes a deep 
yellow or browu color. If we moisten one of these cells 
with nitric acid, tlie cell-wall is not affected, but the 
liquid penetrates it, coagulates the inner membrane, and 
colors it yellow. In the same way this membrane is 
tinged violet-blue by hydrochloric acid. These reactions 
leave no room to doubt that the slimy inner lining of the 
cell or protoplasm contains abundance of albuminoids. 
The protoplasm is not miscible with water and main- 
tains itself distinct from the cell-sap. In young cells it 
is constantly in motion, the granules suspended in it cir- 
culating as in a liquid current. 

If we examine the cells of any other jilant we find 
almost invariably the same structure as above described, 
provided the cells are young, i. e., belong to (jro?ninf/ 
parts. In some cases isolated cells consist only of proto- 
plasm and nucleus, being destitute of cell-walls during 
a portion or the Avhole of their existence. 

In studying many of the maturer parts of plants, viz., 
such as have censed to enlarge, as tlie full-sized leaf, the 
perfectly formed wood, etc., we find the cells do not cor- 
respond to the description just given. In external shape, 
thickness, and appearance of the cell-wall, and csjiecially 
in the character of the contents, there is indefinite va- 
riety. But this is the result of change in the original 
cells, which, so far as our observations extend, are always, 
at first, form6d closely on the pattern that has been de- 
scribed. 

Vegetable Tissue. — It does not, however, usually 
hapi)en that the individual cells of the higher orders of 
plants admit of being obtained separately. They are 
attached together more or less firmly by their outer sur- 
faces, so as to form a coherent mass of cells — a tissue, as 
it is termed. In the accompanying cut. Fig. 30, is shown 
a highly-magnified view of a portion of a very thin slice 



ELEMENTS 0¥ OliGAKlZED STliUCTUEE. 



217 



ticros8 ii young ctibbage-stalk. It exhibits tlic outline of 
the irregular empty cells, the walls of which are, for the 
most i)art, externally united and a])|)ear as one, a. At 
the points indicated by I), air-filled cavities between the 
cells are seen, called intercclhiltw spaces, A slice across 
the potato-tuber (see Fig, 52, p. 300) has a similar ap- 
pearance, except that the cells are filled with starch, and 

it would be scarcely pos- 
sible to dissect them apart; 
but when a potato is boiled 
the starch - grains swell, 
and the cells, in conse- 
quence, separate from each 
other, a practical result of 
which is to make the po- 
tato mealy. A thin slice 
of vegetable ivory (the seed 
of Phytel ej) has macro- 
Fig. 30. cari^ci) under the micro- 

scope, dry or moistened with water, presents no evident 
trace of cell-structure ; however, u})on soaking in sul- 
phuric acid, the mass softens and swells, and the indi- 
vidual cells are revealed, their surfaces separating in 
six-sided outlines. 

Form of Cells. — In the soft, succulent parts of 
plants, the cells lie loosely together, often with consider- 
able intercellular spaces, and have mostly a rounded out- 
line. In denser tissues, the cells are crowded together 
in the least possible space, and hence often ai)pear six- 
sided when seen in cross-section, or twelve-sided if viewed 
entire. A })iece of honey-comb is an excellent illustra- 
tion of the appearance of many forms of vegetable cell- 
tissue. 

The pulp of an orange is the most evident example of 
cell-tissue. The individual cells of the ripe orange may 
be easily separated from each other. Being mature and 




248 



HOW CROPS GEOW. 




incapable of further growth, they possess neither proto- 
plasm nor nucleus, but are filled with a sap or juice con- 
taining citric acid, sugar and albuminoids. 

In the pith of the rush, star-shaped cells are found. 
In common mold the cells are long and 
'ohread-like. In the so-called frog-spittle 
[algce] they are cylindrical and attached 
end to end. In the bark of many trees, 
in the stems and leaves of grasses, they 
are square or rectangular. 

Cotton-fiber, flax, and hemp consist of 
long and slender cells. Fig. 31. Wood is 
mostly made up of elongated cells, tapered 
at the ends and adhering together by 
their sides. See also Fig. 49, c, li, p. 292. 

Each cotton-fiber is a single cell which forms an 
external appendage to the seed-vessel of the cotton 
'plant. When it has lost its sap and become air-dry, 
its sides collapse and it resembles a twisted strap. 
./, in Fig. 31, exhibits a i^ortion of a cotton-fiber 
highly magnified. The ilax-fiber, from the inner 
bark of the fiax-stem, 6, Fig. 31, is a tube of thicker 
walls and smaller bore than the cotton-fiber, and 
hence is more durable than cotton. It is vei'y flexi- 
ble, and even when crushed or bent short retains much of its original 
tenacity. Hemp-fiber closely resembles flax-fiber in appearance. 

Tlrickemu/f of f/ic ('ell- Membrane— The growth of the cell, which, 
when young, lias a very delicate outer 
meml)rane, often results in the thick- 
ening of its walls by the interior dep- 
osition of cellulose and woody mat- 
ters. This thickening may take place 
regularly and uniforndy, or interrupt- 
edly. The flax -fiber, h. Fig. 31, is an ex- 
ample of nearly uniform thickening. 
The irregular deposition of cellulose is 
shown in Fig. 32, which exhibits a sec- -^^q 
tion from the seeds (cotyledons) of the 
c o m m on n a s t u r t i u m ( Tropi^olum ^i&- 33. 

viajns). The original membrane is coated interiorly with several dis- 
tinct and siiccessively-formed linings, which are not continuous, but 
are irregidarly developed. Seen in section, the thickening has a waved 
outline, and, at points, the original cell-membrane is bare. "Were these 
cells viewed entire, we should see at these points, on the exterior of 
the cell, dots or circles appearing like orifices, but being simply the 




ELEMENTS OF OKGAl^LZED STRUCTUKE. 249 

unthickenefl portions of llie cell-wall. The cells in fig. 32 exhibit each 
a centriil nucleus suiiouiided by grains of aleurone. 

Cell Contents. — Besides the protoplasm and nucleus, 
the cell usually contains a variety of bodies, which have 
been, indeed, noticed already as ingredients of the plant, 
but which may be here recapitulated. Many cells are 
altogether empty, and consist of notliing but the cell- 
wall. Such are found in the bark or epidermis of most 
plants, and often in the pith, and although they remain 
connected with the actually living 2)arts, they have no 
longer any proper life in themselves. 

All living or active cells are distended with liquid. 
This consists of water, which holds in solution gum, dex- 
trin, inulin, the sugars, albuminoids, organic acids, and 
other vegetable principles, together with various salts, 
both of organic and mineral acids, and constitutes the 
sap of the plant. In oil-plants, droplets of oil occupy 
certain cells. Fig. 17, p. 83; while in numerous kinds of 
vegetation colored and milky juices are found in certain 
spaces or channels between the cells. 

The water of the cell comes from the soil, or in some 
cases from the air. The matters, which are dissolved in 
the sap of the plant, together with the semi-solid proto- 
plasm, undergo transformations resulting in the produc- 
tion of various solid substances. By observing the sev- 
eral parts of a plant at the successive stages of its devel- 
opment, under the microscope, we are able to trace 
within the cells the formation and growth of starch- 
grains, of granular or crystalline bodies consisting chiefly 
of albuminoids, and of the various matters which give 
color to leaves and flowers. 

The circumstances under which a cell develoj)s deter- 
mine the character of its contents. The outer cells of 
the potato-tuber are incrusted with corky matter, the 
inner ones are for the most part filled witJi starch. 

In oats, wheat, and other cereals, we find, just within 



^50 now ciiops Gitovv. 

the skin or epidermis of the grain, a few hiycrs of cells 
that contain scarcely anything but albuminoids, witli a 
little fat ; while the interior cells are chielly filled with 
starch. Fig. 18, p. 110. 

Transformations in Cell Contents. — The same 
cell may exhibit a great variety of aspect and contents at 
dilferent periods of growth. This is especially to be 
observed in the seed while developing on the mother 
plant. Hartig has traced these changes in numerous 
plants under the microscope. According to this ob- 
server, the cell-contents of the seed (cotyledons) of the 
common nasturtium {Tropceohmi majti^) run through 
the following metamorphoses. Up to a certain stage in 
its development the interior of the cells are nearly devoid 
of recognizable solid matters, other than the nucleus and 
the adhering jn'otojilasm. Shortly, as the growth of the 
seed advances, green grains of chlorophyll make tlx3ir 
appearance upon the nucleus, completely covering it 
from view. At a later stage, these grains, which have 
enlarged and multiplied, are seen to have mostly become 
detached from the nucleus, and lie near to and in contact 
with the cell- wall. Again, in a short time the grains 
lose their green color and assume, both as regards appear- 
ance and deportment with iodine, all the characters of 
starch. Subse(|uently, as the seed hardens and becomes 
firmer in its tissues, the microscope shows that the 
starcli-grains, which were situated near the cell-wall, 
have vanished, while the cell-wall itself has thickened 
inwardly — the starch having been converted into cellu- 
lose or bodies of similar properties. Again, later, the nu- 
cleus, about which, in the meantime, more starch-grains 
have been formed, undergoes a change and disappears ; 
then the starch-grains, some of which have enlarged while 
others have vanished, are found to l)e imbedded in a pasty 
matter, which has the reactions of an albuminoid. From 
this time on^ the starch-grains are gradually converted 



eleme:!?ts of organized structure. 



251 



from their surfaces inwardly into smaller grains of aleu- 
rone, which, finally, when the seed is mature, completely 
occupy the cells. 

In the sprouting of the seed similar changes occur, but 
in reversed order. The nucleus reappears, the aleurone 
dissolves, and even the cellulose* stratified upon the inte- 
rior of the cell (Fig. 32) wastes away and is converted into 
soluble food (sugar ?) for the seedling plant. 




The Oimensions of Vegetable Cells are very vari- 
ous. A creeping marine plant is known — the Caulerpa 
lirolifera (Fig. 33) — which consists of a single cell, though 
it is often a foot in length, and is branched with what 
have the appearance of leaves and roots. The pulp of 

* Or more probably mctarabin, parapalactin, xyliii, or tlie Uke insol- 
uble siibstaiuH-s, whic^h as yetliave been but imperl'ectly distinguished 
from cellulose iu the thickened cell-walls. 



252 



HOW CROPS GROW. 



the orange consists of cells which are one-quarter of an 
inch or more in diameter. The fibei- of cotton is a single 
cell, commonly from one to two inches long. In most 
cases, however, the cells of plants are so small as to re- 
quire a powerful microscope to distinguish them, — are^ 
in fact, no more than j^qq to 200 of an inch in diame- 
ter. The spores of Fungi are still smaller. The germs 
of many bacteria are so minute as to be undiscoverable 
by the liighest powers of the microscope. 

Growth. — The growth of a plant is nothing more 
than the aa'crresfate result of the enJara'ement and multi- 
plication of the cells which compose it. In most cases 
the cells attain their full size in a short time. The con- 
tinuous growth of plants depends, then, chiefly on the 
constant and I'Miud formation of new cells. 

Cell-mulliplication. — The young and active cell 





Fig. 35. 

always contains a nucleus (Fig. 34, h). Such a cell may 
produce a ncAV cell by division. In this process the nu_ 
cleus, from which all cell-growth appears to originat«, is 
observed to resolve itself into two parts, then the proto- 
plasm, a, begins to contract or infold across the cell in a 
line corresponding with the division of the nucleus, until 
the opposite infolded edges meet, — like the skin of a sau- 
sage where a string is tightly tied around it, — thus sepa- 
rating the two nuclei and inclosing each within its new 
cell, which is completed by a further external growth of 
cellulose. 



ELEMENTS OF ORGANIZED STRUCT UKE. 253 

In one-celled plants, like yeast (Fig. 35), tlie new cells 
tlms formed, bud out from the side of the parentrcell, 
and before they obtain full size become entirely detached 
from it, or, as in higher plants, the new cells remain ad- 
hering to the old, forming a tissue. 

In free cell-formation nuclei are observed to develop in 
the protoplasm of a parent cell, which enlai-ge, surround 
themselves with their own protoplasm and cell-membrane, 
and by the resorption or death of the parent cell become 
independent. 

The rapidity with which the vegetable cells may mul- 
tiply and grow is illustrated by many familiar facts. 
The most striking cases of quick growth are met with in 
the mushroom family. Many will recollect having seen, 
on the morning of a June day, huge pulf -balls, some as 
large as a peck measure, on the surface of a moist 
meadow, where the day before nothing of the kind was 
noticed. In such sudden growth it has been estimated 
that the cells are j^i'oduced at the rate of three or four 
hundred millions per hour. 

Permeability of Cells to Liquids. — Although the 
highest magnifying power that can be brought to bear 
upon the membranes of the vegetable cell fails to reveal 
any apertures in them, — they being, so far as the best- 
assisted vision is concerned, completely continuous and 
imperforate, — they are nevertheless readily permeable to 
liquids. This fact may be» shown by placing a delicate 
slice from a potato tuber, immersed in water, under the 
microscope, and then bringing a drop of solution of 
iodine in contact with it. Instantly this reagent pene- 
trates the walls of the unbroken cells without perceptibly 
affecting their appearance, and, being absorbed by the 
starch-grains, at once colors them intensely purplish- 
blue. The particles of which the cell-walls and their 
contents are composed must be separated from each 
other by distances greater than the diameter of the par- 



254: now CROPS grow. 

tides of water or of other liquid matters wbicli thus per- 
meate the cells. 



2. 



THE VEGETABLE TISSUES. 

As already stated, the cells of the higher kinds of 
plants are united together more or less firmly, and thus 
constitute what are known as Vegetable Tissues. Of 
these, a large number have been distinguished by vege- 
table anatomists, the distinctions being based either on 
peculiarities of form or of function. For our purposes 
it will be necessary to define but a few varieties, viz.: 
Cellular Tissue, Wood- Tissue, Bast-Tissue and Vas- 
cular Tissue. 

Cellular Tissue, or Parenchyma, is the simplest of 
all, being a mere aggregation of globular or polyhedral 
cells whose walls are in close adhesion, and whose juices 
commingle more or less in virtue of this connection. 
Cellular tissue is the groundwork of all vegetable struc- 
ture, being the only form of tissue in the simpler kinds 
of plants, and that out of which all the other tissues are 
developed. 

Prosenchyma is a name ap^died to all tissues composed 
of elongated cells, like those of wood and bast. Paren- 
chyma and prosenchyma insensibly shade into each 
other. 

Wood-Tissue, in its simplest form, consists of 
cells that are several or many times as long as they are 
broad, and that taper at each end to a point. These 
spindle-shaped cells cohere firmly together by their sides, 
and "break joints" by overlapping each other, in this 
way forming the tough fibers of wood. Wood-cells are 
often more or less thickened in their walls by depositions 
of cellulose and other matters, according to their age 



VEGETATIVE ORGAXS OF PLANTS. 255 

and position, and arc sometimes dotted and perforated, 
as will bo explained hereafter — Fig. 53, p. 301. 

Bast-Tissue is made up of long and slender cells, 
similar to those of wood-tissue, but commonly more del- 
icate and flexible. The name is derived from the occur- 
rence of this tissue in the bast, or inner bark. Linen, 
hemp, and most textile materials of vegetable origin, 
cotton excepted, consist of bast-fibers. Bast-cells occupy 
a place in rind, corresponding to that held by wood- 
cells in the interior of the stem — Fig. 40, p. 293. 

Vascular Tissue is the term applied to those un- 
branched Tithes and Dvcts which are found in all the 
higher orders of plants, interpenetrating the cellular 
tissue. There are several varieties of ducts, viz., dotted 
ducts, rivged or annular ducts, and spired ducts, of 
which illustrations will be given when the minute struc- 
ture of the stem comes under notice — Fig. 49, p. 293. 

The formation of vascular tissue takes i:)lace by a sim- 
ple alteration in cellular tissue. A longitudinal scries of 
adliering cells represents a tube, save that the bore is 
obstructed with numerous transverse partitions. By the 
removal or perforation of these partitions a tube is devel- 
oped. This removal or perforation actually takes place 
in the living plant by a process of absorption. 



CHAPTER III. 

THE VEGETATIVE ORGANS OF PLANTS. 

§ 1- 
THE ROOT. 

The roots of plants, witli few exceptions, from the 
first moment of their devehipment, grow downward. In 
general, they require a moist medium. They will form 
in water or in moist cotton, and in many cases originate 
from branches, or even leaves, when these parts of the 
plant are buried in tlie earth or immersed in water. It 
cannot be assumed that they seek to avoid the light, 
because they may attain a full development without 
being kept in darkness. The action of light upon them, 
however, appears to be unfavorable to their functions. 

The Growth of Roots occurs mostly by lengthen- 
ing, and very little or very slowly by increase of thick- 
ness. The lengthening is chiefly manifested toward the 
outer extremities of the roots, as was neatly demonstrated 
by Wigand, who divided the young root of a sprouted 
pea into four equal parts by ink-marks. After three 
days, the first two divisions next the seed had scarcely 
lengthened at all, while the third was double, and the 
fourth eight times its previous length. Ohlerts made 
precisely similar observations on the roots of various 
kinds of plants. The grov/th is confined to a space of 
about one-sixth of an inch from the tip. (Linnca, 1837, 
jip. G09-G31.) This peculiarity adapts the roots to 
extend through the soil in all directions, and to occujoy 
256 



VEGETATIVE ORGAl^S OF PLAKTS. 



257 



its smallest pores, or rifts. It is likewise the reason that 
a. root, which has been cut oU in transplanting or other- 
wise, never afterwards extends in length. 

Although the older parts of the roots of trees and of 
the so-called root-crops acquire a considerable diameter, 
the roots by which a plant feeds are usually thread-like 
and often exceedingly slender. 

Spongioles. — The tips of the rootlets have been 
termed spongioles, or spongelets, from the idea that 
their texture adapts them especially to collect food for 
the plant, and that the absorption of matters from the 
soil goes on exclusively through them. In this sense, 
spongiQks_.da_rLot- exist. The real living apex of the 
root is not, in fact, the outmost extremity, but is situ- 
ated a little within that point. 

Root-Cap. — The extreme end of the root usually con- 
sists of cells that have become loosened and in part 

detached from the proper cell-tis- 
sue of the root, which, therefore, 
shortly perish, and serve merely 
as an elastic cushion or cap to 
protect the true termination or 
living point of the root in its act 
of penetrating the soil. Fig. 36 
represents a magnified section of 
part of a barley root, showing the 
loose cells which slough off from 
the tip. These cells are filled 
with air instead of sap. 

A striking illustration of the 
root-cap is furnished by the air- 
roots of the so-called Screw Pine 
(Pandanus odorafissimus), exhibited in natural dimen- 
sions, in Fig. 37. These air-roots issue from the stem 
above the ground, and, growing downwards, enter the 
soil, and become roots in the ordinary sense. 
17 




Fi.i--. 36. 



258 



now CHOPS GROW. 



When fresh, the diameter of the root is quite uni- 
form, but the parts above tlie root-cap shrink on dry- 
ing, while the root-cap itself retains 
nearly its original dimensions, and 
thus reveals its different structure. 

Distinction between Root and 
Stem. — Not all the subterranean 
parts of the plant are roots in a 
proper sense, although commonly 
spoken of as such. The tubers of 
the potato and artichoke, and the 
fleshy horizontal parts of the sweet- 
flag and pepper-root, are merely 
underground stems, of which many 
varieties exist. 

These and all other stems are 
easily distinguished from true roots 
by the imbricated buds, of which 
indications may usually be found on 
their surfaces, e. g., the eijes of the 
potato-tuber. The side or second- 
ary roots are indeed marked in their 
earliest stages by a protuberance on 
the primary root, but these have noth- 
ing in common with the structure of 
true buds. The onion-bulb is itself 
a fleshy bud, as will be noticed snbse- Fig. 37. 

quently. The true roots of the onion are the fibers 
which issue from the base of the bulb. The roots of 
many plants exhibit no buds upon their surface, and are 
incapable of developing them under any conditions. 
Roots of other plants, such as the plum, apple, and pop- 
lar, may pr(xluce buds when cut off from the parent 
plant during the growing season. The roots of the 
former perish if deprived of connection with the stem 
and leaves. The latter may strike out new stems and 




Iff'-- '- 





VEGETATIVE ORGANS OF PLANTS. 259 

leaves for themselves. Plants like the plum are, there- 
fore, capable of propagation by root-cuttings, 1. e., by 
placing pieces of their roots in warm and moist earth. 

Tap-roots. — All plants whose seeds divide into two 
seed-leaves or Cotyledons, and whose stems increase 
externally by addition of new rings of growth— the 
Dicotyledonous idlants, or Exogens—\\i\sQ, at first, a single 
descending axis, the tap-root, which penetrates vertically 
into the ground. From this central tap-root lateral 
roots branch out more or less regularly, and these lateral 
roots subdivide again and again. In many cases, espec- 
ially at first, the lateral roots issue from the tap-root 
with great order and regularity, as much as is seen in 
the branches of the stem of a fir-tree or of a young grape- 
vine. In older plants, this order is lost, because the 
soil opposes mechanical hindrances to regular develop- 
ment. In many cases the tap-root grows to a great 
length, and forms the most striking feature of the radi- 
cation of the plant. In others it enters the ground but 
a little way, or is surpassed in extent by its side branches. 
The tap-root is conspicuous in the Canada thistle, dock 
(Rumex), and in seedling fruit trees. The upper por- 
tion of the tap-root of the beet, turnip, carrot, and rad- 
ish expands under cultivation, and becomes a fleshy, 
nutritive mass, in which lies the value of these plants 
for agriculture. The lateral roots of other plants, as of 
the dahlia and sweet potato, swell out at their extremi- 
ties to tubers. 

Crown Roots. — Monocotyledonous jjlants, or Endo- 
gens, i. e., plants whose embryos have only one seed- 
leaf, or Cotyledony and whose stems do not increase by 
external additions, such as the cereals, grasses, lilies, 
palms, etc., have no single descending axis or tap-root, 
l3ut produce crotvn roots, i. e., a number of roots issue 
at once from the base of the stem. This is strikingly 
seen in the onion and hyacinth, as well as in maize. 



260 HOW CROPS GROW. 

Rootlets. — This term we apply to the slender roots, 
but a few inclies long, which ai-e formed last in the 
order of growth, and correspond to the larger roots as 
twigs correspond to the branches of the stem. 

Toe Offices of the Root arc threefold : 

1. To fix the plant in the earth and maintain it in an 
erect position. 

2. To absorb nutriment from tlie soil for the growth 
of the entire plant, and, 

3. In case of many plants, especially of those whose 
terms of life extend through several or many years, to 
serve as a store-house for the future use of the plant. 

1. The Firmness with which a Plant is fixed in 
the Ground depends upon the nature of its roots. It 
is easy to lift an onion from the soil ; a carrot requires 
much more force, while a dock may resist the full 
strength of a powerful man. A small beech or seedling 
apple tree, which has a tap-root, withstands the force of 
a wind that would prostrate a maize-plant or a poplar, 
which has only side roots. In the nursery it is the cus- 
tom to cut off the tap-root of apple, peach, and other 
trees, wdien very young, in order that they may be readily 
and safely transplanted as occasion shall require. The 
depth and character of the soil, however, to a certain 
degree iulluence the extent of the roots and the tenacity 
of their hold. The roots of maize, which in a rich 
and tenacious earth extend but two or three feet, have 
been traced to a length of ten or even fifteen feet in 
a light, sandy soil. The roots of clover, and especially 
those of alfalfa, extend very deej)ly into the soil, and the 
latter acquire in some cases a length of 30 feet. The 
roots of the ash have been known as much as 95 feet 
long. {Jour. Roy. Ag. Soc, VI, p. 343.) 

2. Root-absorption. — The Office of Absorbing 
Plant Food from the Soil is one of the utmost impor- 
tance, and one for which the root is most wisely adapted 
by the following particulars, viz. : 



VEGETATIVE OllGANS OF PLANTS. 261 

a. The Delicacy of its Structure, especially that of the 
newer portions, the cells of which are very soft and ab- 
sorbent, as may be readily shown by immersing a young 
seedling bean in solution of indigo, when the roots 
shortly acquire a blue color from imbibing the liquid, 
while the stem is for a considerable time unaltered. 

It is a common but erroneous idea that absorption 
from the soil can only take place through the ends of the 
roots — through the so-called spongioles. On the con- 
trary, the extreme tips of the rootlets cannot take up liq- 
uids at all. (Ohlerts, loc. cit.y see p. 270.) All other 
parts of the roots, which are still young and delicate in 
surface-texture, are constantly active in the work of im- 
bibing nutriment from the soil. 

In most perennial plants, indeed, the larger branches 
of the roots become after a time coated with a corky or 
otherwise nearly impervious cuticle, and the function of 
absorption is then transferred to the rootlets. This is. 
demonstrated by placing the old, brown-colored roots of 
a plant in water, but keeping the delicate and unindu- 
rated extremities above the liquid. Thus situated, the 
plant withers nearly as soon as if its root- surface were all 
exposed to the air. 

b. Its Bapid Extension in Length, and the va'^t Sur- 
face which it puts in contact with the soil, further adapts 
the root to the work of collecting food. The length of 
roots in a direct line from the point of their origin is 
not, indeed, a criterion by which to judge of the effi- 
ciency wherewith the plant to Avhich they belong is nour- 
ished ; for two plants may be equally flourishing — be 
equally fed by their roots — when these organs, in one 
case, reach but one foot, and in the other extend two feet 
from the stem to v/hich they are attached. In one case, 
the roots v/ould be fewer and longer ; in the other, 
shorter and more numerous. Their aggregate length, 
or, more correctly, the aggregate absorbing surface, 
would be nearly the same in both. 



262 HOV/ CROPS GROW. 

The Medium in loldch Roots Orotic has a great influ- 
ence on tlicir extension. Wlien tliey are situated in con- 
centrated solutions, or in a very fertile soil, they are 
short, and numerously branched. Where their food is 
sparse, they are attenuated, and bear a comparatively 
small number of rootlets. Illustrations of the former 
condition are often seen ; moist bones and masses of 
manure are not infrequently found, completely covered 
and penetrated by a fleece of stout roots. On the other 
hand, the roots which grow in poor, dry soils are very 
lon^' and slender. 

ISTobbe has described some experiments which com- 
jDletely establish the point under notice. {Vs. St., lY, 
p. 212.) He allowed maize to grow in a poor clay soil, 
contained in glass cylinders, each vessel having in it a 
quantity of a fertilizing mixture disposed in some pecu- 
liar manner for the purpose of observing its influence on 
the roots. When the plants had been nearly four months 
in growth, the vessels were placed in water until the earth 
was softened, so that by gentle agitation it could be com- 
pletely removed from the roots. The latter, on being 
suspended in a glass vessel of water, assumed nearly the 
position they had occupied in the soil, and it was ob- 
served that, where the fertilizer had been thoroughly 
mixed with the soil, the roots uniformly occupied its 
entire mass. Where the fertilizer had been placed in a 
horizontal layer at the depth of about one inch, the roots 
at that depth formed a mat of the finest fibers. W^here 
the fertilizer was situated in a horizontal layer at half the 
depth of the vessel, just there the root system was sphe- 
roidally expanded. In the cylinders where the fertilizer 
formed a vertical layer on the interior walls, the external 
roots were developed in numberless ramifications, while 
the interior roots were comparatively unbranched. In 
pots, where the fertilizer was disposed as a central vertical 
core, the inner roots were far more greatly developed 



VEGETATIVE ORGAKS OF PLANTS. 2G3 

than the outer ones. Finally, in a vessel where the fer- 
tilizer was jjlaced in a horizontal layer at the bottom, 
the roots extended through the soil, as attenuated and 
sliglitly branched fibers, until they came in contact with 
the lower stratum, where they greatly increased and ram- 
ified. In all cases, the principal development of the 
roots occurred in the immediate vicinity of the material 
wliich could furnish them with nutriment. 

It has often been observed that a plant whose aerial 
branches are symmetrically disposed about its stem, has 
the larger share of its roots on one side, and again we find 
roots which are thick with rootlets on one side and 
nearly devoid of them on the other. 

A'piiarcnt Searcli for Food. — It would almost appear, 
on sujierficial consideration, that roots are endowed with 
a kind of intelligent instinct, for they seem to go in 
search of nutriment. 

The roots of a plant make their first issue independ- 
ently of the nutritive matters that may exist in their 
neighborhood. They are organized and put forth from 
tlie plant itself, no matter how fertile or sterile the me- 
dium that surrounds them. When they attain a certain 
development, they are ready to exercise their office of 
collecting food. If food be at hand, they absorb it, and, 
together with the entire plant, are nourished by it — they 
grow in consequence. The more abundant the food, the 
better they are nourished, and the more they multiply. 
The plant sends out rootlets in all directions ; those 
which come in contact with food, live, enlarge, and ram- 
ify ; those which find no nourishment, remain undevel- 
oped or perish. 

The Qumitity of Roots actually belonging to any Plant 
is usually far greater than can be estimated by roughly 
lifting them from the soil. To extricate the roots of 
wheat or clover, for example, from the earth, completely, 
is a matter of extreme difficulty. Schubart was the first 



2G4 HOW CHOPS GROW. 

to make satisfactory observations on the roots of several 
imiDoriant crops, growing in the field. He separated 
them from the soil by the following expedient : An exca- 
vation was made in the field to the depth of 6 feet, and 
a stream of water was directed against the vertical wall 
of soil until it was washed away, so that the roots of the 
plants growing in it were laid bare. The roots. thus ex- 
posed in a field of rye, in one of beans, and in a bed of 
garden peas, presented the appearance of a mat or felt of 
white fibers, to a depth of about 4 feet from the surface 
of the ground. The roots of winter wheat he observed 
as deep as 7 feet, in a light subsoil, forty-seven days after 
sowing. The depth of the roots of winter wheat, winter 
rye, and winter colza, as well as of clover, was 3 to 4 feet. 
The roots of clover, one year old, were S|- feet long, those 
of two-year -old clover but four inches longer. The quan- 
tity of roots in per cent of the entire plant in the dry 
state was found to be as follows. {Chem. Achersmann, 
I, p. 193.) 

Winter wheat— examined last of April 40% 

<■<■ " «« " "May 22" 

«« rye " " "April 34" 

Peas examined four weeks after sowing 44 " 

" " at the time of blossom ...24" 

Ilelliiegcl has likewise studied the radication of barley 
and oats {Hoff, JaUresbericlit, 18G4, p. lOG.) He raised 
plants in large glass pots, and separated their roots from 
the soil by careful washing with water. He observed 
that directly from the base of the stem 20 to 30 roots 
branch-off sideways and downward. These roots, at 
their point of issue, have a diameter of ^^ of an inch, 
but a little lower the diameter diminishes to about y^^ of 
an inch. Retaining this diameter, they pass downward, 
dividing and branching to a certain depth. From these 
main roots branch out innumerable side roots, which 
branch again, and so on, filling every crevice and pore of 
the soil. 



VEGETATIVE ORGANS OF PLANTS. 



2G5 



To ascertain the total length of root, Hellriegel weighed 
and ascertained the length of selected average portions. 
Weighing then the entire root-system, be calculated the 
entire length. He estimated the length of the roots of a 
vigorous barley plant at 1;^8 feet, that of an oat plant at 
150 feet.* He found that a small bulk of good fine soil 
siifhced for this development ; ^V cubic foot (4 -|- 4 + ^4 
in.) answered for a barley plant, 3^ cubic foot for an 
oat plant, in these experiments. 

Hellriegel observed also that the quality of the soil in- 
fluenced the development. In rich, porous, garden-soil, 
a barley plant produced 128 feet of 
roots, but in a coarse-grained, com- 
pacter soil, a similar plant had but 80 
feet of roots. 

Boot Hairs, — The real absorbent 
surface of roots is, in most cases, not 
to be appreciated without microscopic 
aid. The roots of the onion and of 
many other bulbs, i. e., the fibers which 
issue from the base of the bulbs, are per- 
fectly smooth and unbranched through- 
out their entire length. Other agricul- 
tural plants have roots which are not 
only visibly branched, but whose finest 
fibers are more or less thickly covered 
with minute hairs, scarcely perceptible 
to the unassisted eye. These root-hairs 
consist always.-of tubular elongations of 
the external root-cells, and through 
them the actual root-surface exposed 
to the soil beo'omes something almost 
Fig. 38. incalculable. The accompanying fig- 

ures illustrate the appearance of root-hairs. 

Fig. 38 represents a young mustard seedling. A is 

*ltlicnish, 34= o5 EugUsh feet. 




2CG 



HOW CROPS GROW. 



the plant, as carefully lifted from the sand in which it 
grew, and B the same plant, freed from adhering soil 
by agitating in water. The entire root, save the tip, 
is thickly beset with hairs. In Fig. 39 a minute portion 
of a barley-root is shown highly magnified. The hairs 
arc seen to be slender tubes that proceed from, and form 
part of, tlie outer cells of the root. 

The older roots lose their hairs, and suffer a thicken- 
ing of the outermost layer of cells. These dense- walled 
and nearly impervious cells cohere together and consti- 
tute a rind, which is not found in the young and active 
roots. 

As to the development of the 
root-hairs, they are more abund- 
ant in poor than in good soils, 
and appear to be most numer- 
ously produced from roots which 
have otherwise a dense and un- 
absorbent surface. The roots of 
those plants which are destitute 
of hairs are commonly of consid- 
erable thickness and remain 
white and of delicate texture, 
preserving their absorbent power 
throughout the whole time that the plant feeds from the 
soil, as is the case with the onion. 

The Silver Fir {Ahies Picea) has no root-hairs, but its 
rootlets are covered with a very delicate cuticle highly 
favorable to absorption. The want of root-hairs is fur- 
ther compensated by the great number of rootlets which 
are formed, and which, perishing mostly before they be- 
come superficially indurated, are continually replaced by 
new ones during the growing season. (Schacht, Der 
Baum, p. 1G5.) 

Confad of Roofs with the Soil. — The root-hairs, as 
they extend into the soil, are naturally brought into close 




Fie:. 39. 



VEGETATIVE OllGAifS OF PLAifTS. 



2m 




Wig. 40. 



Fig. 41 



268 



HOW CROPS GROW. 



contact with its particles. This contact is much more 
intimate tlian has been usually su})posed. If we care- 
fully lift a young wheat-plant from dry earth, we notice 
that each rootlet is coated with an envelope of soil. This 
adheres with considerable tenacity, so that gentle shak- 
ing fails to displace it, and if it be mostly remoyed by 




Fig. 42. 

vigorous agitation or washing, tlie root-hairs are either 
found to be broken, or in many places insei^arably at- 
tached to the particles of earth. 

Fig. 40 exhibits the appearance of a young wheat- 



VEGETATIVE ORGANS OF PLANTS. 



2G9 



plant as lifted from the soil and pretty strongly shaken. 
S, the seed; I), the 'blade ; e, roots covered with hairs 
and enveloped in soil. Only the growing tips of the 
roots, w, which have not put forth hairs, come out clean 
of soil. Fig. 41 represents the roots of a wheat-plant 
one month older than those of the previous figure. In 
tills instance not only the root-tips are naked as before, 
but the older parts of the primary roots, e, and of the 
secondary roots, n, no longer retain the particles of soil ; 
the hairs upon them being, in fact, dead and decom- 
posed. The newer parts of the root alone are clothed 
with active hairs, and to these the soil is firmly attached 
as before. The next illustration. Fig. 42, exhibits the 

appearance of root-hairs with ad- 
hering particles of earth, when mag- 
nified 800 diameters : A, root-hairs 
of wheat-seedling, like Fig. 40; B, 
of oat-plant, both from loamy soil. 
Here is plainly seen the intimate 
attachm.ent of the soil and rcot- 
hairs. The latter, in forcing their 
w^ay against considerable pressure, 
often expand arouml, and partially 
envelo}), , the particles of earth. 
(Sachs's Fxp. Phys. tl. Pflanzen.) 
[mhlhitioii of water hy the root. — 
The force with which active roots 
imbibe the water of the soil is 
snfficicnt to force the liquid upward (i yy 
into the stem and to exert a continu- 
al pressure on all i)arts of the plant. 
When the stem of a plant in vigor- 
ous growth is cut off near the root, 
^ig- 43. .^jj(^[ a pressure-gauge is attached to 

it, as in Fig. 43, we have the means of observing and 
measuring the force with which the roots absorb water. 




270 now CROPS GROW. 

The jircss 11 re-gun gc contains a qnantity of mercnry in 
the middle reservoir, h, and the tnbe, c. It is attached 
to the stem of tlie plant, j*^, by a stout india-rubber 
pipe, ^.* For accurate measurements, the space a and 
h should be tilled with water. Thus arranged, it is found 
that water will enter a through the stem, and the mer- 
cury will rise in the tube, e, until its pressure becomes 
sufficient to balarce the absorptive, power of the roots. 
Stephen Hales, who first experimented in this manner 
(1721) found in one instance that the pressure exerted 
on a gauge, attached in spring time to the stump of a 
grape-vine, supported a column of mercury Z2\ inches 
high, which is equal to a column of water of 36| feet, 
llofmeister obtained on other plants, rooted in pots, the 
following results : 

Bean (Phaseolus multiflorus) 6 inches of mercnry. 

Nettle 14 " " 

Vine 29 " " 

The seat of absorption Dutrochet demonstrated to be 
the surface of the young and active roots. At least, he 
found that absorption was exerted with as much force 
when the gauge was applied to near the lower extremity 
of a root as when attached in the vicinity of the stem. 
In fact, when other conditions are alike, the column of 
liquid sustained by the roots of a plant is greater the less 
the length of stem that remains attached to them. The 
stem tlius resists the rise of liquid in the plant. 

While the seat of absorptive power in the root lies 
near the extremities, it ai)pears from the experiments of 
Ohlerts that the extremities themselves are incapable of 
imbibing water. In trials with young pea, flax, lupine 
and horseradish plants with unbranched roots, he found 
that they withered speedily when the tips of the roots 
were immersed for about one-fourth of an inch in water, 



*F()v experimentin}? on small i)lants, a simple tube of p;lass may bo 
adjusted to the stump vertically by help of a rubber connector. 



VEGETATIVE 0RGA:N^S OF PLANTS. 271 

the remaininn^ parts being in moist air, Ohlerts like, 
wise proved that these plants flourish when only iho 
middle part of their roots is immersed in water. Keejj- 
ing the root-tips, the so-called spongioles, in the air, or 
cutting them away altogether, was without apparent 
effect on the freshness and vigor of the plants. The 
absorbing surface would thus appear to be confined to 
those portions of the root upon which the development 
of root-hairs is noticed. 

The absorbent force is manifested by the active root- 
lets, and most vigorously when these are in the state of 
most rapid development. For this reason we find, in 
case of the vine, for example, that during the autumn, 
when the plant is entering uj)on a period of repose from 
growth, the absorbent power is trifling. Sometimes 
water is absorl^ed at the roots so forcibly as not oidy to 
distend the plant to the utmost, but to cause the sap of 
tlie plant to exude in drops upon the foliage. This may 
be noticed upon newly-sprouted maize, or other cereal 
plants, where the water escapes from the leaves at their 
extreme tips, especially when the germination has pro- 
ceeded under the most favorable conditions for rapid 
development. 

The bleeding of the vine, when severed in the spring- 
time, the abundant flow of sap from the sugar-maple 
and the water-elm, are striking illustrations of this 
imbibition of water from the soil by the roots. These 
examples are, indeed, exceptional in degree, but not in 
kind. Hofmeister has shown that the bleeding of a sev- 
ered stump is a general fact, and occurs with all plants 
when the roots are active, when the soil can supply them 
abundantly with water, and when the tissues above the 
absorbent parts are full of this liquid. When it is other- 
wise, water may be absorbed from the gauge into the 
stem and large roots, until the conditions of activity are 
renewed. 



272 HOW CROPS GROW. 

Of the external circumMances tliat affect this absorp- 
tive power, heat and light would apjiear to be influential. 
By observing a gauge attached to the stump of a plant 
during a clear summer day, it will be usually noticed 
that the mercury begins to rise in the morning as the 
sun warms the soil, and continues to ascend for a num- 
ber of hours, but falls again as the sun declines. Sachs 
found in some of his experiments that, in case of plotted 
tobacco and squash plants, absorption was nearly or 
entirely suppressed by cooling the roots to 41° F., but 
was at once renewed by plunging the pots into warm 
water. 

The external supplies of water, — in case a plant is 
stationed in the soil, the degree of moisture contained in 
this medium, — obviously must influence any manifesta- 
tion of the imbi])ing force. But full investigation sliows 
that this regular daily fluctuation is a habit of the plant 
wliich is independent of small changes of temperature 
and even of considerable variation in the amount of mois- 
ture of the soil. 

The rate of absorption is subject to changes depend- 
ent on causes not well understood. Sachs observed 
that the amount of liquid which issued from potato 
stalks cut off just above the ground underwent great 
and continual variation from hour to hour (during rainy 
weather) when the soil was saturated with water and 
when the thermometer indicated a constant temperature. 
Hofmeister states that the formation of new roots and 
buds on the stump is accompanied by a sinking of the 
water in the pressure-gauge. 

Absorption of Nutriment from tlie Soil. — The food of 
the plant, so far as it is derived from the soil, enters it 
in a state of solution, and is absorbed witli the water 
which is taken up by the rootlets. The absorption of 
the matters dissolved in water is in some dec-ree inde- 
pendent of the absorption of the water itself, the i^lant 



VEGETATIVE ORGANS OF PLANTS. 273 

having apj)arently, to a certain extent, a selective power. 
See p. 401. 

3. The Root as a Magazine. — In Fleshy Taj)- 
Roots, like those of the carrot, beet, and turnip, the 
absorption of nutriment from the soil takes place princi- 
pally, if not entirely, by means of the slender rootlets 
which proceed abundantly from all their surface, and 
especially from their lower extremities, while the older 
fleshy part serves as a magazine in which large quantities 
of carbhydrates, etc., are stored up during the first year's 
growth of these liennial plants, to supply the wants of 
the flowers and seed which are developed the second year. 
When one of these roots, put into the ground for a sec- 
ond year, has produced seed, it is found to l)e quite 
exhausted of the nutritive matters which it previously 
contained in so large quantity. 

Root 7'uI)crs,\\kG those of the dahlia and sweet potato, 
are flesliy enlargements of lateral or secondary roots 
filled with reserve material, from which buds and new 
stems may develop. Sm.all tubers (Tnhercles) are fre- 
quently formed on the roots of the garden bean 
{Pliascolus). 

In cultivation, the farmer not only greatly increases 
the size of these roots and the stores of organic nutritive 
materials they contain, but, by removing them from the 
ground in autumn, he employs to feed himself and his 
cattle the substances that nature primarily designed to 
nourish the growth of flowers and seeds during another 
summer. 

Soil-Roots ; Water-Roots ; Air-Roots. — We may 
distinguish, according to the medium in which they are 
formed and grow, three kinds of roots, viz.: soil-roots, 
water-roots, and air-roots. 

Most agricultural plants, and indeed by far the greater 
number of all plants found in temperate climates, have 
roots adapted especially to the soil, and which i-)erish by 
18 



274 now CROPS grow. 

short exposure to dry air, or rot, if long immersed in 
water. Many aquatic plants, on the other hand, speed- 
ily die when their roots are removed from water, or from 
earth saturated witli water, and exposed to the atmos- 
pliere or stationed in earth of the usual dryness. 

Air-roots are not common except among tropical plants 
or under tropical conditions of heat and moisture. In- 
dian corn, when thickly planted and of rank growth, 
often throws out roots from the lower joints of the stem, 
which extend through the air several inches before they 
reach the soil. The same may be observed of many com- 
mon plants, as the oat, grape, potato, and l)uckwheat, 
when they long remain in hot, moist air. Tlie Banyan- 
tree of India sends out from its branches, vertically, 
pendants several yards long which penetrate the earth 
and there become soil-roots. 

On the other hand, various tropical plants, especially 
Orchids, emit roots which hang free in the air and never 
reach the earth. In the humid forest ravines of Madeira 
and Teneriffe, the Lauriis Cannriensis, a large tree, 
sends out from its stem, during the autumn rains, a pro- 
fusion of fleshy air-roots, which cover the trunk with 
their interlacing branches and grow to an inch in thick- 
ness. The following summer they dry away and fall to 
the ground, to be replaced by new ones in the ensuing 
autumn. (Schacht, Der Baum, p. 172.) 

A plant, known to botanists as the Zamia spiralis, not 
only throws out air-roots, c c. Fig. 44, from the crown of 
the main soil-root, but the side rootlets, h, after extend- 
ing some distance horizontally in the soil, send, from the 
same point, roots downward and upward, the latter of 
which, d^ pass into and remain permanently in the air. 
a is the stem of the plant. (Schacht, Afiatoinie dcr 
Geiodchse, Bd. II, p. 151.) 

The formation of air-roots may be very easily observed 
by placing water to the depth of half an inch in a tall 



VEGRTATTYE OKGANR OF PLATifTS. 



275 



vial, inserting a sprig of the common greenhonsc-plant 
Tradcscanria zebrina, so that the cut end of the stem 
shall stand iu the water, and finally corking the vial air- 
tight. The plant, which is very tenacious of life, and 
usually grows well in spite of all neglect, is not checked 
in its vegetative development by the treatment just de- 
scribed, but immediately begins to adapt itself to its 
new circumstances. In a few days, if the temperature 
be 70° or thereabout, air-roots will be seen to issue from 
the joints of the stem. These are fringed with a profu- 
sion of delicate hairs, and rapidly extend to a length of 
from one to two inches. The lower ones, if they chance 




Fig. 44. 
to penetrate the water, become discolored and decay ; the 
others, however, remain for a long time fresh, and of a 
white color. 

Some plants have roots which are equally able to exist 
and perform their functions, whether in the soil or sub- 



276 HOW CROPS GROW. 

merged in water. Many forms of yegctation found in 
our swamps and marshes are of this kind. Of agricul- 
tural plarts, rice is an example in point. Eice will grow 
in a soil of ordinary cliaracter, in respect of moisture, as 
the upland cotton-soils, or even the pine-barrens of the 
Carolinas. It liourishes admirably in the tide-swamps of 
the coast, where the land is laid under water for Aveeks 
at a time during its growth, and it succeeds equally Avell 
in fields which are flowed fi'om the time of planting to 
that of harvesting. (Russell, North America, its Agri- 
culture and Climate, p. 176.) The willow and akler, 
trees which grow on the margins of streams, send a part 
of tlieir roots into soil that is constantly saturated with 
water, or into the water itself ; while others occupy the 
merely moist or even dry earth. 

Plants that customarily confine their growth to the 
soil occasionally throw out roots as if in search of water, 
and sometimes choke up drain-pipes or even wells by the 
profusion of water-roots which they emit. At Welbeck, 
England, a drain was completely stopped by roots of 
liorsc-radish plants at a depth of 7 feet. At Thornsby 
Park, a drain 16 feet deep was stopped entirely by the 
roots of gorse, growing at a distance of 6 feet from the 
drain. {Jour. Roy. Ag. Soc, I, p. 364.) In New 
Haven, Connecticut, certain wells are so obstructed by the 
aquatic roots of the elm trees as to require cleaning out 
every two or three years. This aquatic tendency has 
been repeatedly observed in the poplar, cypress, laurel, 
turnip, mangel-wurzel, and various grasses. 

Ilenrici surmised that the roots which most cultivated 
plants send down deep into the soil, even when the latter 
is by no means porous or inviting, are designed esjiecially 
to bring up water from the subsoil for the use of the 
plant. He devised the following experiment, which ap- 
pears to prove the truth of this view. On the 13th of 
May, 1862, a young raspberry plant, having but two 



YEGETATIYE OIIGANS OF PLANTS. 277 

leaves, was transplanted into a large glass funnel filled 
with garden soil, the throat of the funnel being closed 
with a paper filter. The fnnnel was supported in the 
mouth of a large glass jar, and its neck reached nearly to 
the bottom of the latter, where it just dipped into a 
quantitv of water. The soil in the funnel was at first 
kept moderately moist by occasional waterings. The 
plant remained fresh and slowly grew, putting forth new 
leaves. After tlic lapse of several weeks, four strong 
roots penetrated the filter and extended down the empty 
funnel-neck, through which they emerged, on the 21st 
of June, and thenceforward spread rapidly in the water 
of the jar. From this time on, the soil was not watered 
anymore, but care was taken to maintain the supply in 
the jar. The plant continued to develop slowly ; its 
leaves, however, did not acquire a vivid green color, Imt 
remained pale and yellowish; they did not wither until 
the usual time, late in autumn. The roots continued to 
grow, and filled the water more and more. Near the 
end of December the plant had seven or eight leaves, and 
a height of eight inches. The water- roots were vigorous, 
very long, and beset with numerous fihrils and buds. In 
the funnel tube the roots made a perfect tissue of fibers. 
In the dry earth of the funnel they were less extensively 
developed, yet exhibited some juicy buds. The stem 
and the young axillary leaf-buds v/ere also full of sap. 
The water-roots beir.g cut away, the plant was put into 
garden soil and placed in a conservatory, v/here it grew 
vigorously, and in May bore two offshoots. {Hcnneber(fs 
J OUT. far Landwirthscliaft, 1863, p. 280.) This growth 
towards water must be accounted for on the principles 
asserted in the paragraph. Apparent Search for Food 
(p. 263). 

The seeds of many ordinary land plants — of plants, 
indeed, that customarily grow in a dry soil, such as the 
bean, squash, maize, etc. — will readily germinate in 



278 now cRors grow. 

moist cotton or sawdust, and if, when fairly sprouted, 
the young plants have their roots suspended in water, 
taking care that the seed and stem are kept above the 
liquid, they will continue to grow, and with due supplies 
of nutriment will run through all the customary stages 
of development, produce abundant foliage, blossoms, and 
perfect seeds, without a moment's contact of their roots 
with soil. (See Water Culture, p. 181.) 
^4^ In j)lants thus growing with their roots in a liquid 
medium, after they have formed several large leaves, be 
carefully transplanted to the soil, they wilt and perish, 
unless frequently watered ; whereas similar plants, started 
in the soil, may be transplanted without suffering in the 
slightest degree, though the soil be of the usual dryness, 
and receive no water. 

The water-bred seedlings, if abundantly watered as 
often as the foliage wilts, recover themselves after a time, 
and thenceforward continue to grow without the need of 
Avatering. 

It might appear that the first-formed water-roots are 
incapable of feeding the plant from a dry soil, and hence 
the soil must be at first profusely watered ; after a time, 
however, new roots are thrown out, which are adapted to 
the altered situation of the plant, and then the growth 
proceeds in the usual manner. 

The reverse experiment would seem to confirm this 
view. If a seedling that has grown for a short time only 
in the soil, so that its roots are but twice or thrice 
branched, have these immersed in water, the roots 
already formed mostly or entirely perish in a short time. 
They indeed absorb water, and the plant is sustained by 
them, but immediately ncAV roots grow from the crown 
with great rapidity, and take the place of the original 
roots, which become disorganized and useless. It is, 
however, only the young and active rootlets, and those 
covered with hairs, which thus refuse to live in water. 



VEGETATIVE ORGAKS OF PLANTS. 270 

The older purts of the roots, whicli are destitute of fibrils 
and which have nearly ceased to be active in the work of 
absorption, are not affected by the change of circum- 
stance. These facts, which are due to the researches of 
Dr. Sachs (Vs. St., II, p. 13), would naturally lead to 
the conclusion that the absorbent surface of the root un- 
dergoes some structural change, or produces new roots 
with modified characters, in order to adapt itself to the 
medium in which it is placed. It would appear that 
when this adaptation proceeds rapidly the plant is not 
permanently retarded in its growth by a gradual change 
in the character of the medium which surrounds its 
roots, as may happen in case of rice and marsh -plants, 
when the saturated soil in which they may be situated at 
one time is slowly dried. Sudden changes of medium 
about the roots of plants slow to adapt themselves would 
be fatal to their existence. 

Nobbe has, however, carefully compared the roots of 
buckwheat, as developed in the soil, with those emitted 
in water, without being able to observe any structural 
differences. The facts above detailed admit of partial, if 
not complete, explanation, without recourse to the suppo- 
sition that soil- and water-roots are essentially diverse in 
nature. When a plant which is rooted in the soil is 
taken up so that the fibrils are not broken or injured, 
and set into water, it does not suffer any hindrance in 
growth, as Sachs found by his later experiments. (Bx- 
pcrimenial Phi/siolof/ie, p. 177.) Ordinarily, the susi)en- 
sion of growth and decay of fibrils and rootlets is duo, 
doubtless, to the mechanical injury they suffer in remov- 
ing from the soil. Again, when a plant that has been 
reared in water is ])lantcd in earth, similar injury occurs 
in packing the soil about the roots, and moreover the 
fibrils cannot be brought into tluit close contact with the 
soil which is necessary for them to supply the foliage 
with water ; hence the plant wilts, and may easily perish 



280 now CROPS geow. 

unless profusely watered or shielded from evaporation. 

The air-roots of Orchids, which never reach the soil, 
have a peculiar sponofy texture and take up the water 
which exists as vapor in the air, as shown by the experi- 
ments of linger, Ohatin, and Sachs. Duchartre's inves- 
tigations led him to deny their absorptive power. [Ele- 
ments cle Botmiiqiie, p. 21G.) In. his experiments made 
on entire plants, the air-roots failed to make good the 
loss by evaporation from the other parts of the plant. 

It is evident from common observation that 77ioistnre 
is the condition that chiefly determines root-develop- 
ment. Not only do all seeds sprout and send forth roots 
when provided with abundant moisture at suitable tem- 
peratures, but generally older roots and stems, and 
fleshy leaves, or cuttings from these, will produce new 
rootlets when properly circumstanced as regards moisture, 
whether that moisture be supplied by aid of a covering 
of damp soil, wet sand or paper, by stationing in humid 
air, or by immersion in water itself. 

Root-Excretions. — It was formerly supposed that 
the roots of plants perform a function of excretion, the 
reverse of absorption — that plants, like animals, reject 
matters which are no longer of use in their organism, 
and that the rejected matters are poisonous to the kind 
of vegetation from which they originated. Do Oandolle, 
an eminent French botniiist, who first advanced this doc- 
trine, founded it n})on the observation that certain })lants 
exude dr()j)s of li(|uid from their I'oots when these are 
placed in dry sand, and that odors exhale from the roots 
of other plants. Numerous experiments have been in- 
stituted at various times for the purpose of testing this 
question. Noteworthy are those of Dr. Alfi-ed Gyde 
(Trails. Highlmid and Af/r. Si>c., 1845-47, pp. 273-92). 
This experimenter planted a variety of agricultural plants, 
viz., wheat, barley, oats, rye, beans, peas, vetches, cab- 
bage, mustard, and turnips, in pots filled either with 



VEGETATIVE ORGANS OF PLANTS. 281 

garden ^oU, simd, moss, or cluircoal, and after tbej had 
attained considerable growth, removed the earth, etc., 
from their roots by Avashing with water, using care not 
to injure or wound them, and then immersed the roots 
in vessels of pure water. The plants were allowed to re- 
main in these circumstances, their roots being ke])t in 
darkness, but their foliage exposed to light, from three 
to seventeen days. In most cases they continued appa- 
rently in a good state of health. At the expiration of 
the time of experiment, the water which had been in 
contact with the roots was evaporated, and was found to 
leave a very minute amount of yellowish or brown mat- 
ter, a portion of which was of organic and the remainder 
of mineral origin. Dr. Gyde concluded that plants do 
throw off organic and* inorganic excretions similar in 
composition to their sap ; but that the quantity is ex- 
ceedingly small, and is not injurious to the plants which 
furnish them. 

In the light of newer investigations touching the 
structure of roots and their adaptation to the medium 
which happens to invest them, we may well doubt 
whether agi-icultural plants in the healthy state excrete 
any solid or liqnid matters whatever from their roots. 
The familiar excretion of gum, resin, and sugar* from 
the stems of trees api)ears to result from wounds or dis- 
ease, and the matters which in the experiments of Gyde 
and others were observed to be communicated by the 
roots of plants to ])ure water jirobably came either from 
the continual pushing off of tiie tips of the rootlets Ijy 
the interior growing point— a process always naturally 
accomi)anying the growth of roots — or from the disor- 
ganization of the absorbent root-hairs. 

Under certain circumstances, small quantities of sol- 
uble salts or free acids may indeed diffuse out of the 

* From the wounded bark of tlie sugar-pine (Pi;ir<s Lambcrtiana) of 
California. ^ 



282 now CROPS grow. 

root-cells into the water of the soil. This is, however, 
no physiological action, but a purely physical process. 

Vitality of Roots. — It appears that in case of most 
plants the roots cannot long continue their vitality if 
their connection with the leaves be interrupted, unless, 
indeed, they be kept at a winter temperature. Hence 
weeds may be effectually destroyed by cutting down 
their tops ; although, in many cases, the process must 
be several times repeated before the result is attained. 

The roots of our root-crops, properly so-called, viz., 
beets, turnips, carrots, and parsnips, when harvested in 
autumn, contain the elements of a second year's growth 
of stem, etc., in the form of a bud at the crown of the 
root. If the crown be cut away from the root, the latter 
cannot vegetate, while the growth of the crown itself is 
not thereby prevented. 

As regards internal structure, the root closely resem- 
bles the stem, and what is stated of the latter, on subse- 
quent pages, applies in all essential points to the former. 



2. 



THE STEM. 

Shortly after the protrusion of the rootlet from a ger- 
minating seed, the Stem makes its ap[)earance. It has, 
in general, an upward direction, which in many plants 
is ])ermanent, while in others it shin'tly falls to the 
ground and grows thereafter horizontally. 

All plants of the higher orders have stems, though in 
many instances they do not appear above ground, but 
extend beneath the surface of the soil, and are usually 
considered to be roots. 

While the root, save in exceptional cases, does not 
develop other organs, it is the special function of the 
stem to bear the leaves, llowers, and seed of the plant. 



VEGETATfVE ORGANS OF PLANTS. 



283 



and even in certain tribes of vegetation, like the cacti, 
which have no leaves, to perform the offices of these 
organs. In general, the functions of the stem are sub- 
ordinate to those of the organs which it bears — the leaves 
and flowers. It is the support of these organs, and, it 
would appear, only extends in length or thickness with 
the purpose of sustaining them mechanically or provid- 
ing them with nutriment. 

Buds. — In the seed the stem exists in a rudimentaiy 
state, associated with undeveloped leaves, forming a had. 
The stem always proceeds at first from a bud, during all 
its growth is terminated by a bud at every growing point, 
and only ceases to be thus tipped when it fully accom- 
plislies its growth by the production of seed, or dies 
from injury or disease. 

In the leaf -hud we find a number of embryo leaves 
and leaf-like scales, in close contact and within each 
other, but all at- 
tached at the base 
to a central conical 
axis, Fig. 45. The 
opening of the bud 
consists in the 
lengthening of this 
axis, which is the 
stem, and the con- 
sequent separation 
from each other as 
well as expansion of 
the leaves. If the 
rudimentary leaves of a bud be represented by a nest of 
flower-pots, the smaller placed within the larger, the 
stem may be signified by a rope of India-rubber passed 
through the holes in the bottom of the pots. The 
growth of the stem may now be shown by stretching the 
rope, whereby the pots arc brought away from each 





Fig. 45. 



284 now CROPS grow. 

other, and tlic whole combination is made to assume the 
character of a fully-developed stem, bearing its leaves at 
regular intervals ; with these important diiierences, that 
the portions of stem nearest the root extend more rap- 
idly than those above them, and the stem has within it 
the material and the mechanism for the continual for- 
mation of new buds, which unfold in successive order. 

In Fig. 45, which represents the two terminal buds of 
a lilac twig, is shown not only the external appearance 
of the buds, which are covered with leaf-like scales, 
imbricated like shingles on a roof ; but, in the section, 
are seen the edges of the undeveloped leaves attached to 
the conical axis. All the leaves and the whole stem of 
a twig of one summer's growth thus exist in the bud, in 
plan and in miniature. Subsecfuent growth is but the 
development of the plan. 

In the flmver-bud the same structure is manifest, save 
that the rudimentary flowers and fruit are enclosed 
within the leaves, and may often be seen plainly on cut- 
ting the bnd open. 

Nodes; Internodes. — Nodes are those knots or parts 
of the stem where the leaves are attached. The portions 
of the stem between the nodes are termed internodes. 
It is from the nodes that roots most freely develop when 
stems (layers or cuttings) are surrounded by moist air or 
soil. 

Culms. — The grasses and the common cereal grains 
have single, unbranched stems, termed culms in botani- 
cal language. The leaves of these plants clasp the stem 
entirely at their base, and rest upon a well-defined, thick- 
ened node. 

Branching Stems. — Other agricultural plants besides 
those just mentioned, and all the trees of temperate cli- 
mates, have iranching stems. As the principal or main 
stem elongates, so that the leaves arranged upon it sepa- 
rate from each other, we find one or more buds at the 



VEGETATIVE ORGAN'S OF PLANTS. 285 

point where the base of the leaf or of the leaf -stalk 
unites with the stem. From these axillary buds, in case 
their growth is not checked, side-stems or branches 
issue, which again subdivide in the same manner into 
branchlets. 

In perennial plants, when young, or in their young 
shoots, it is easy to trace the nodes and internodes, or 
the points where the leaves are attached and the inter- 
vening spaces, even for some time after the leaves, which 
only endure for one year, are fallen away. The nodes 
are manifest by the enlargement of the stem, or by the 
scar, covered with corky matter, which marks the spot 
where the leaf-stalk was attached. As the stem grows 
older these indications of its early development are grad- 
ually obliterated. 

In a forest where the trees arc thickly crowded, the 
lower branches die away from want of light ; the scars 
resulting from their removal, or short stumps of the 
limbs themselves, are covered with a new growth of 
wood, so that the trunk finally appears as if it had always 
been destitute of branches, to a great height. 

When all the buds develop normally and in due pro- 
portion, the plant, thus regularly built up, has a sym- 
metrical appearance, as frequently happens with many 
herbs, and also with some of the cone-bearing trees, 
especially tlie balsam-fir. 

Latent Buds. — Often, however, many of the buds 
remain undeveloped, either permanently or for a time. 
Many of the side-buds of most of our forest and fruit 
trees fail entirely to grow, while others make no progress 
until the summer succeeding their first appearance. 
When the active buds arc destroyed, either by frosts or 
by pinching off, other buds that would else remain 
latent are pushed into growth. In this way trees 
whose young leaves are destroyed by spring frosts cover 
themselves again, after a time, with foliage. In this way. 



286 now CRors grow. 

too, the gardener molds a straggling, ill-shaped shrub or 
plant into almost any form he chooses ; for, by removing 
branches and buds where they have grown in undue pro- 
portion, lie not only checks excess, but also calls forth 
development in the parts before suppressed. Close 
pruning or breaking the young twigs causes abundant 
development of flower-buds on fruit trees that otherwise 
*'run to wood." 

Adventitious or irregular Buds are produced from 
the stems as well as older roots of many plants, when 
they are mechanically injured during the growing season. 
The soft or red maple and the chestnut, when cut down, 
habitually throw out buds and new stems from the 
stump, and the basket-Avillow is annually polled, or pol- 
larded, to induce the growth of slender shoots from an 
old trunk. 

Elongation of Stems. — Wliile roots extend chiefly 
at their extremities, we find the stem elongates equally, 
or nearly so, in all its contiguous parts, as is manifest 
from what has already been stated in illustration of its 
development from the bud. 

Besides the ui)right stem, there are a variety of pros- 
trate and in part su])terranean stem;-i, which may bo 
briefly noticed. 

Runners and L-ayers are stems that are sent out hor- 
izontally just above the soil, and, coming in contact with 
the earth, take root, forming new plants, which may 
thenceforward grow independently. The gardener takes 
advantage of these stems to propagate certain plants. 
The strawberry furnishes the most familiar example of 
runners, while many of the young shoots of the currant 
fall to the j>;round and become layers. The runner is a 
somewhat peculiar stem. It issues horizontally, and 
usually bears but few or no leaves. The layer does not 
dilfcr from an ordinary stem, except by the circum- 
stance, often accidental, of becoming prostrate. Many 



VEGETATIVE ORGAN^S OF PLANTS. 287 

plants which usually send out no layers are nevertheless 
artificially layered by bending their stems or branchec to 
the oTound, or by attaching to them a ball or pot of 
earth. The striking out of roots from the layer i,s in 
many cases facilitatod by cutting half through, twisting^ 
or otlierwise wounding the stem at the point where it is 
buried in the soil. 

The iillering of wheat and other cereals, and of many 
grasses, is the spreading of the plant by layers. The first 
stems that appear from those j^hmts ascend vertically, 
but, subsequently, other stems issue, Avhose growth is, 
for a time, nearly horizontal. They thus come in con- 
tact with the soil, and emit roots from their lower joints. 
From these again grow new stems and new roots in rapid 
succession, so that a stool produced from a single kernel 
of winter wheat, having perfect freedom of growth, has 
been known to carry 50 or GO grain-bearing culms. 
(Ilallet, Jour. Roy. Soc. of Eny., 23, p. 372.) 

Suckers. — When branches arise from the stem below 
the surface of the soil, so that they are partly subter- 
ranean and partly aerial, as in the Rose and Easpberry, 
they are termed Suckers. These leafy shoots put out 
roots from their buried nodes, and may be separated 
artificirJly and used for propagating the plant. 

Subterranean Stems. — Of these there are three 
forms. They are usually taken to be roots, from the 
fact of existing below the surface of the soil. This cir- 
cumstance is, however, quite accidental. The pods of 
the peanut {Ar acids liyiiogcBo) ripen beneath the 
ground — the flower-stems lengthening and penetrating 
the earth as soon as the blossom falls ; but these stems 
are not by any means to be confounded with roots. 

Root-stocks, or Rhizomes. — True roots are desti- 
tute of leaves. This fact easily distinguishes them from 
the rhizome, which is a stem that extends below the sur- 
face of the ground. At the nodes of these root-stocks^ 



288 



now cEors grow. 



as they are appropriately named, scales or rudimentary 
leaves are seen, and thence roots proper are emitted. In 
the axils of the scales may be traced the buds from which 
aerial and fruit-bearing stems proceed. Examples of 
the root-stock are very common. Among them we may 
mention the blood-root and j)epper-root as abundant in 
the woods of the Northern and Middle States, various 
mints, asparagus, and the quack-grass (Agropyrum* 
repe7is) represented in Fig. 46, which infests so many 
farms. Each node of the root-stock, being usually sup- 
plied with roots, and having latent buds, is ready to 
become an independent growth the moment it is detached 




Fiir. 4G. 



from its parent plant. In this way quack-grass becomes 
especially troublesome, for the more tlie fields where it 
has obtained a footing: are tilled the more does it com- 
monly spread and multiply; only oft-repeated harrow- 
ing in a season of prolonged dryness suffices for its 
extirpation. 

Corms are enlargements of the base of the stem, bear- 
ing leat'-buds either at the summit or side, and may be 
regarded as much-shortened rhizomes, with only a few 
slightly-developed internodes. Externally they resemble 
bulbs. The garden crocus furnishes an example. 

Tubers of many plants are fleshy enlargements of the 



♦Formerly Triticum. 



VEGETATIVE ORGANS OF PLAN"TS. 289 

extremities of subterranean stems. Tlicir eyes are tlie 
points where the buds exist, iisnally three together, 
and where minute scales — rudimentary leaves — may be 
observed. The common potato and artichoke {Helian- 
thus tuiero&us) are instances of this kind of tubers. 
Tubers serve excellently for propagation. Each eye, or 
bud, may become a new plant. From the quantity of 
starch, etc., accumulated in them, they are of great 
importance as food. The number of tubers produced by 
a potato-plant appears to be increased by planting orig- 
inally at a considerable depth, or by "hilling up" earth 
around the base of the aerial stems during the early 
stages of its growth. 

Bulbs are greatly thickened stems, whose leaves — 
usually having the form of fleshy scales or concentric coats 
— are in close contact with each other, and arise from 
nearly a common base, the internodes being undeveloped. 
The bulb is, in fact, a permanent bud, usually in part 
or entirely subterranean. From its apex, the proper 
stem, the foliage, etc., proceed; while from its base 
roots are sent out. The structural identity of the bulb 
with a bud is shown by the fact that the onion, which 
furnishes the commonest example of the bulb, often 
bears bulblets at the top of its stem, in place of flowers. 
In like manner, the axillary buds of tlie tiger-lily are 
thickened and fleshy, and fall off as bulblets to the 
ground, where they produce new plants. 

Structure of the Stem. — The stem is so compli= 
cated that to discuss it fully would occupy a volume. 
For our immediate purposes it is, however, only neces- 
sary to notice its structural composition very concisely. 

The rudimentary stem, as found in the seed, or the 
new-formed part of the maturer stem at the growing 
points just below the terminal buds, consists of cellular 
tissue, or is an aggregate of rounded and cohering cells, 
which rapidly multiply during the vigorous growth of 
the plant. 19 



290 HOW CROPS GROW. 

In some of the lower orders of vegetation, as in mush- 
rooms and lichens, the stem, if any exist, always pre- 
serves a purely cellular character ; but in all flowering 
plants the original cellular tissue of the stem, as well as 
of the root, is shortly penetrated by vascular tissue, 
consisting of ducts or tubes, which result from the 
obliteration of the horizontal partitions of cell-tissue, 
and by loood-cells, which are many times longer than 
wide, and the walls of wliich are much thickened by 
internal deposition. 

These ducts and wood-cells, together with some other 
forms of cells, are usually found in close connection, and 
are arranged in hitndlcs, which constitute the fibers of 
the stem. They are always disposed lengthwise in the 
stem and branches. They are found to some extent in 
the softest herbaceous stems, while they constitute a 
large share of the trunks of most shrubs and trees. 
From the toughness which they ^wssess, and the manner 
in Avhich they are woven through the original cellular 
tissue, they give to the stem its solidity and strength. 

Flowering plants may be divided into two great classes, 
in consequence of important and obvious differences in 
the structure of their stems and seeds. These are : 1, 
Monocotyledons, or Endogens ; and 2, Dicotyledons, or Exo- 
gens. As regards their stems, these two classes of plants 
differ in the arra;ngement of the vascular or woody tissue. 

Endogenous Plants are those whose stems enlarge by 
the formation of new wood in the interior, and not by 
the external growth of concentric layers. The embryos 
in the seeds of endogenous plants consist of a single piece 
— do not readily split into halves — or, in botanical lan- 
guage, have but one cotyledon; heiice are called monoco- 
tyledonous. Indian corn, sugar-cane, sorghum, wheat, 
oats, rye, barley, the onion, asparagus, and all the 
grasses, belong to this tribe of plants. 

If a stalk of maize, asparagus^ or bamboo be cut 



VEGETATIVE ORGANS OF PLANTS. 291 

across, tlie fiber-like bundles of ducts and wood-cells are 
seen disposed somewhat uniformly throughout the sec- 
tion, though less abundantly towards the center. On 
splitting the fresh stalk lengthwise, these vascular bun- 
dles may be torn out like strings. At the nodes, vvhero 
the stem is branched, or where leaf-stalks are attached, 
the vascular bundles likewise divide and form a net-work. 
In a ripe maize-stalk which is exposed to circumstances 
favoring decay, the soft cell-tissue first suffers change 
and often quite disappears, leaving the firmer A^ascular 
bundles unaltered in form. A portion of the base of 
such a stalk, cut lengthwise, is represented in Fig. 47, 
where the vascular bundles are seen arranged parallel to 
each other in the internodes, and curiously interwoven 
and branched at the nodes, both at those {a and h) from 
which roots issued, or at that (c) which was clasped by 
the base of a leaf. 

1l^\\q endogenous stem, as represented in the maize- 
stalk, has no well-defined hark that admits of being- 




stripped off externally, and no separate central pith of 
soft cell-tissue free from vascular bundles. It, like the 
aerial portions of all flowering i:)lants, is covered with a 
skin, or epidermis, composed usually of one or several 
layers of flattened cells, whose walls are thick, and far 
less penetrable to fluid than the delicate texture of the 
interior cell-tissue. The stem is denser and harder at 
the circumference than towards the center. This is due 
to the fact that the bundles are more numerous and 
older tov/ards the outside of the stem. The newer bun- 
dles, as they continually form at the base of the growing 
terminal biid, pass to the inside of the stem, an^ affer- 



292 



now CROPS GROW. 



wards outwards and dovfnwards, and hence the designa- 
tion endogenous, which in plain English means inside- 
grower. 

In consequence of this inner growth, the stems of 
most woody endogens, as the palms, after a time become 
so indurated externally that all lateral expansion ceases, 
and the stem increases only in height. In some cases, 
the tree dies because its interior is so closely j^acked with 




Fi- 48. 



bundles that the descent of new ones, and the accom- 
panying yital processes, become impossible. 

In herbaceous endogens the soft stem admits the 
indefinite growth of new vascular tissue. 



VEGETATIVE ORGAKS OF PLANTS. 



293 



The stems of the grasses are liollow, except at the 
nodes. Those of the rushes have a central pith free from 
vascular tissue. 

The Minute Structure of the Endogenous Stem 
is exhibited in the accompanying cuts, wirich represent 
highly magnified sections of a Vascular Bundle or fiber 
from the maize-stalk. As before remarked, the stem is 
composed of a groundwork of delicate cell-tissue, in 
which bundles of vascular-tissue are distributed. Fig. 
48 represents a cross section of one of these bundles, c, 
g, h, as well as of a portion of the surrounding cell-tis- 




Fig. 49. 

sue, a, a. The latter consists of quite large cells, which 
have between them considerable inter-cellular spaces, i. 
The vascular bundle itself is composed externally of 
narrow, thick-walled cells, of which those nearest the 
exterior of the stem, h, are termed last-cells, as they 
correspond in character and position to the cells of the 
bast or inner bark of our common trees ; those nearest 
the center of the stem, c, are luood-cells. In the maize 
stem, bast-cells and wood-cells are qnite alike, and are 



294 HOW CROPS GROW. 

distinguished only by tlieir position. In other plants, 
they are often unlike as regards length, thickness, and 
pliability, though still, for the most part, similar in 
form. Among the wood-cells we observe a number of 
ducts, d, c, f, and between these and tlie bast-^cells is a 
delicate and transparent tissue,.^, which is the cimihimn, 
iu which all the groiutli of the bundle goes on until it 
is complete. On either hand is seen a remarkably large 
duct, 1), h, while the residue of the bundle is composed 
of long and rather thick-walled wood-cells. 

Fig. 49 represents a section made vertically through 
the bundle from c to lb. In this the letters refer to the 
same parts as in the former cut : a, a \& the cell-tissue, 
enveloping the vascular bundle ; the cells are observed 
to be much longer than wide, but are separated from 
each other at the ends as well as sides by an im]:)erforate 
membrane. The wood and bast-cells, c, h, are seen to 
be long, narrow, thick-walled cells running obliquely to 
a point at either end. The wood-cells of oak, hici^ory, 
and the toughest woods, as well as the bast-cells of flax 
n.nd henip, are quite similar in form and appearance. 
The proper ducts of the stem are next in the order of 
our section. Of these there are several varieties, as ring- 
ducts, d; sjnral ducts, e; dotted ducts, f. These are 
continuous tubes produced by the absorption of the 
transverse membranes that once divided them into such 
cells as a, a, and they are thickened internally by ring- 
like, spiral, or punctate depositions of cellulose (see Fig. 
32, p. 248). Wood or bast-cells that consist mainly of 
cellulose are pliant and elastic. It is the deposition of 
other matters (so-called Hg?ii7i) in their walls which ren- 
ders them stiff and brittle. 

At g, the cambial tissue is observed to consist of del- 
icate cylindrical cells. Among these, partial absorption 
of the separating membrane often occurs, so that they 
communicate directly with each other through sieve-like 



VEGETATIVE ORGAN'S OF PLANTS. 



295 



partitions, and become continuous channels or ducts. 
(Sieve-cells, j). 303.) The camMum is the seat of growth 
by cell-formation. Accordingly, when a vascular bun- 
dle has attained maturity, it no longer possesses a cam- 
bium. 

To complete our view of the vascular bundle, Fig. 50 
represents a vertical section made at right angles to the 
last, cutting two large ducts, h, h; a, a is cell-tissue; 




c, c are bast or wood-cells less thickened by interior 
deposition tlian those of Fig. 49 ; <^ is a ring and spiral 
duct ; d, t are large dotted ducts, which exhibit at g, a 
the places where they were once crossed by the double 
membrane composing the ends of two adhering cells, by 
Wiiose absorption and removal an uninterrupted tube 
has been formed. In these large dotted ducts there 
appears to be no direct communication with the sur- 
rounding cells through their sides. The dots or pits 
are simply very thin points in tlie cell-wall, through 
which sap may soak or dilfuse laterally, but not flow. 



296 HOW CROPS GROW. 

When the cells become mature and cease growth, the 
pits often become pores by absor2:)tion of the membrane, 
so that the ducts thus enter into direct communication 
with each other. 

Exogenous Plants are those whose stems contin- 
ually enlarge in diameter by the formation of new tissue 
near the outside of the stem. They are outside-growers. 
Their seeds are usually made np of two loosely-united 
parts, or cotyledons, wherefore they are designated 
dicotyledonous. All the forest trees of temperate cli- 
mates, and, among agricultural phmts, the bean, pea, 
clover, 2^otato, beet, turni}), flax, etc., are exogens. 

In the exogenous stem the bundles of ducts and fibers 
that appear in the cell-tissue are always formed just 
within the rind. They occur at first separately, as in 
the endogens, but, instead of being scattered throughout 
the cell-tissue, are disposed in a circle. As they grow, 
they usually close up to a ring or zone of wood, which 
incloses unaltered cell-tissue — the pith. 

As the stem enlarges, new rings of fibers may be 
formed, but always outside the older ones. In hard 
stems of slow growth the rings are close together and 
chiefly consist of very firm wood-cells. In the soft stems 
of herbs tlic cellular tissue preponderates, and the ducts 
and cells of the vascular zones are delicate. The harden- 
ing of herbaceous stems which takes place as they become 
mature is due to the increase and induration of the 
wood-cells and ducts. 

The circular disposition of the fibers in the exogenous 
stem may be readily seen in a multitude of common 
plants. 

Tlie potato tuber is a form of stem always accessible 
for observation. If a potato be cut across near tlie stem- 
end with a sharp knife, it is usually easy to identify upon 
the section a ring of vascular-tissue, the general course 
of which is parallel to the circumference of the tuber 



VEGETATIVE ORGAN'S OF PLAKTS. 297 

except wliero it runs out to the surface in the eyes or 
buds, and in the narro\y stem at whose extremity it 
grows. If a slice across a potato be soai<:ed in solution 
of iodine for a few minutes, the vascular ring becomes 
strikingly apparent. In its active cambial cells, albu- 
minoids are abundant, which assume a yellow tinge with 
iodine. The starch of the cell-tissue, on the other hand, 
becomes intensely blue, making the vascular tissue all 
the more evident. 

Since the structure of the root is quite similar to that 
of the stem, a section of the common beet as well as one 
of a branch from any tree of temperate latitudes may 
serve to illustrate the concentric arrangement of the vas- 
cular zones when they are multipled in number. 

Fitli is the cell-tissue of the center of the stem. In 
young stems it is charged with juices ; in older ones it 
often becomes dead and sapless. In many cases, espec- 
ially when growth is active, it becomes broken and nearly 
obliterated, leaving a hollow stem, as in a rank pea-vine, 
or clover-stalk, or in a hollow potato. • In the potato 
tuber the pith-cells are occupied throughout with starch, 
although, as the coloration by iodine makes evident, the 
fpiantity of starch diminishes from the vascular zone 
towards the center of the tuber. 

The Bind, which, at first, consists of mere epider7nis, 
or short, thick-walled cells, overlying soft cellular tissue, 
becomes penetrated with cells of unusual length and 
tenacity, which, from their position in the plant, are 
termed bast-cells. These, together with ducts of various 
kinds, constitute the so-called last, which grows chiefly 
upon the interior of the rind, in successive annual layers, 
in close proximity to the wood. With their abundant 
development and with age, the rind becomes harh as it 
occurs on shrubs and trees. The bast-cells give to the 
bark its peculiar toughness, and cause it to come off the 
stem in long and pliant strij)s. 



298 now CROPS grow. 

All the vegetable textile materials employed in the man- 
ufacturo of cloth and cordage, with the exception of cot- 
ton, as flax, hemp, New Zealand flax, etc., are bast-fibers. 
(Seep. 248.) 

In some plants the annual layers of bast are so sepa- 
rated by cellular tissue that in old stems they may be 
split from one another. Various kinds of matting are 
made by weaving together strips of bast layers, especially 
those of the Linden (Bass-wood or Bast-wood) tree, Tlie 
leather-wood or moonc-wood bark, often employed for 
tyinii; flour-bags, has bast-fibers of extraordinary tenacity. 
The bast of the grape-vine separates from the stem in 
long shreds a year or two after its formation. 

Tlie epidermis of young stems is replaced, after a cer- 
tain age, by the corky layer. This differs much in dif- 
ferent plants. In the Birch it is formed of alternate 
layers of large- and small-celled tissue, and splits and 
curls up. From the Plane-tree it is thrown off period- 
ically in large plates hy the expansion of the cellular tis- 
sue underneath. In the Maple, Elm, and Oak, especially 
in the Cork-Oak, it receives animal additions on its 
inner side and does not separate : after a time it conse- 
quently ac([uires considerable thickness, the growtli of 
the stem furrows it with deep rifts, and it gradually 
decays or drops away exteriorly as the newer bark forms 
within. 

Pith Bays. — Those portions of the first-formed cell- 
tissue wiiich v/ere interposed between the young and 
originally ununited wood-fibers remain, and connect the 
pith with the cellular tissue of the bark. They inter- 
rupt the straight course of the bast- cells, producing the 
not ted appearance often seen in l^ast layers, as in the 
Lace-bark. In hard stems they become flattened l)y 
the pressure of the fibers, and are readily seen in most 
khids of wood when split lengthwise. They are espe- 
cially conspicuous in the Oak and Maple, and form what 



VP:GETAT1VE OKGAiNti OF PLANTS. 



Of 



00 




is commonly known as the silver-grain. Tlio botimist 

terms tliem pith-rays, or medullary 
rays. 

Fig. 51 exhibits a section of 
spruce wood, magnified 200 di- 
ameters. The section is made 
fengthwise of the wood-cells, four 
of which are in part represented, 
and cuts across the pith-rays, 
whose cell-structure and position 
in the wood are seen at m, n. 

Branches have tlie same struct- 
ure as the stems from which they 
spring. Their tissues traverse 
those of the stem to its center, 
where they connect with the pith 
and its sheath of spiral ducts. 

CamMiim of Exogens. — The 
growing part of the exogenous 
stem is between the fully formed wood and the ma- 
ture bark. There is, in fact, no definite limit where 
wood ceases and bark begins, for they are connected by 
the cambial or formative zone, from which, on the one 
hand, wood-fibers, and on the other, bast-fibers, rapidly 
develop. In the cambium, likewise, the pith-rays which 
connect the inner and outer parts of the stem continue 
their outward growth. 

In spring-time the new cells that form in the cambial 
region are very delicate and easily broken. For this 
reason tlie rind or bark may be stripped from the wood 
without difficulty. In autumn these cells become thick- 
ened and indurated — become, in fact, full-grown bast and 
wood -cells — so that to peel the bark off smoothly is im- 
possible. 

Minute Structure of Exogenous Stems. — The ac- 
companying figure (52) will serve to convey an idea of 



Fi^. 51. 



300 



now CiiOPo GliOW. 



the minnte structure of the elements of the exogenous 
stem. It exhibits a section Icnytlindse, through a young 
potato tuber magnified 200 diameters ; a, h is the rind ; 
e tlie vascuhir ring ; / tlie pith. The outer cells of the 
rind are converted into cork. They have become empty 
of sap and are nearly impervious to air and moisture. 
This corky-layer, a, constitutes the thin coat or skin that 
may be so readily peeled oli' from a boiled potato. When- 
ever a potato is superficially wounded, even in winter 
time, the exposed part hoa^s over by the formation of 




cork-cells. The cell tissue of the rind consists at its 
center, h, of full-formed cells with delicate membranes 
wdiich contain numerous and large starch grains. On 
either hand, as the rind approaches the corky-layer or 
the vascular ring, the ceils are smaller, and contain 
smaller stareli grains ; at either side of these are noticed 
cells containing no starch, but having miclei, c. y. These 
nucleated cells are capable of multiplication, and they 
arc situated where the growth of the tuber takes place. 
The rind,* wdiicli makes a large part of the flesh of the 
potato, increases in thickness by the formation of new 
cells wnthin and without. Without, wdiere it joins the 
corky skin, tlie latter likew^ise grows. Within, contigu- 



*Tlie word rind is lierp usod in its liotanical (not in the ordinary) 
sense, to denote tliat part of the tuber wliieh corresponds to the rind of 
the stem. 



VEGETATIVE ORGANS OF PLANTS. 



301 



a 



ous to the vascular zone, new ducts are formed. In a 
similar manner, the pith expands by 
formation of new cells, where it joins 
the vascular tissue. The latter consists, 
in our figure, of ring, spiral, and dotted 
ducts, like those already described as 
occurring in the maize-stalk. The deli- 
cate cambial cells, c, are in the region of 
I most active growth. At this point new 
1 cells rapidly develop, those to the right, 
' j'^ in the figure, remaining plain cells and 
I becoming loosely filled with starch ; 
'^^ II A¥<^-V those to the left developing new ducts. 
In the slender, overground potato- 
stem, as in all the stems of most agri- 
cultural plants, the same relation of 
parts is to be observed, although the 
vascular and woody tissues often pre- 
ponderate. Wood -cells are especially 
abundant in those stems that need 
strength for the fulfilment of their offices, 
and in them, especially in those of our 
trees, the structure is commonly more 
CO m pi i c afed"^ " 

Pitted Wood-Cells of the Coni- 
fers. — In the wood of cone-bearino- trees 
'=■ ^^' there are no proper ducts, such as have 

been described. The large wood-cells which constitute 
the concentric rings of the Avood are constructed in a spe- 
cial manner, being provided laterally with pits, or, accord- 
ing to Schacht, with visible pores, through which the 
fluid contents of one cell may easily diffuse (by osmose), 
or even pass directly into those of its neighbors. 

Fig. 53, B represents a portion of an isolated wood-cell 
of the Scotch Fir (Pifius ^ylvestris) magnified 200 diam- 
eters. Upon it are seen nearly circular disks, x, y, the 



30^ 



HOW Clio PS GltOW. 



atractiire of which, while the cell is young, is shown by 
a section through them lengthwise. A exhibits such a 
section through the thickened walls of two contii:!Uous 
and adhering cells, x, in both A and B, shows a cavity 
between the two primary cell-walls ; p is the narrow 
])art of the channel, that 



remains while the mem- 
brane thickens around it. 
This is seen at y, as a pit 
in each cell-wall, or, as 
Schacht believed, a pore 
or o})cning from cell to 
cell. In A it appears 
closed because the section 
passes a little to one side 
of the pore. (Schacht.) 

In the next ligure (54), 
representing a transverse 
section of the spring wood 
of the same tree magnified 
300 diameters, the struct- 
ure and the gradual form- 
ation of these pore-disks 
is made evident. The sec- 
tion, likewise, gives an in- 
structive illustration o f 
the general character of the 
simplest k i n d of w ( )od . E •. 
are tlie young cells of the 
rind ; C is the cambium, 
where cell-multiplication 




Fig. 54. 



goes on; ]|' is the wood, whose cells are more developed 
the older they are, i. e., the more distant from the cam- 
bium, as is seen from their figure and the thickness of 
their walls. At a is shown the disk in its earliest stage ; 
b and c exhibit it in a more advanced growth. At d the 



VEGETATIVE ORGAKS OF PLA:NTR. 303 

disk has become a pore, the primary membrane has been 
absorbed, and a free clumnel made between the two cells. 
The dotted lines at d lead out laterally to two concentric 
circles, which represent the disk-pore seen flatwise, as in 
Fig. 53. At e the section 2)asses through the new 
annual ring into the autumn wood of the preceding year. 
Sieve-cells, or Sieve-ducts. — The spiral, ring, and 
dotted ducts and pitted wood-cells already noticed, ap- 
pear only in the older parts of the vascular bundles, and, 
although they may be occupied with sap at times when the 
stem is surcharged with water, tliey are ordinarily filled 
with air alone. The real transmission of tlie nutritive) 
juices of the growing i)lant, so_fciT as it goes on through y 
actual tubes, is now admitted to proceed in an independ- \ 
enFset of ducts, the so-called sieve-tubes, which are usu-^ 
ally near to and originate from the cambium. These 
are extremely delicate, elongated cells, whose transverse 
or lateral walls are perforated, sieve-fashion (by absorp- 
tion of the original membrane) so as to establish direct 
communication from one to another, and this occurs 
while they are yet charged with juices and at a time 
wlien the other ducts are occupied with air alone. These ) 
sieve-ducts are believed to be the channels through Avhich 
the organic matters that are formed in the foliage mostly y 
pass in their downward movement to nourish the stem -3 
and root. Fig. 55 represents the sieve-cells in the over- 
ground stem of the potato -, A, B, cross-section of parts 
of vascular bundle ; A^ exterior part towards rind ; B, 
interior portion next to pith ; a, a, cell-tissue inclosing 
the smaller sieve-cells, A, B, which contain sap turbid 
with minute granules ; h, cambium cells ; c, wood-cells 
(which are absent in the potato tuber) ; d, ducts inter- 
mingled with wood-cells. C represents a section length- 
wise of the sieve-ducts ; and D, more highly magnified, 
exhibits the finely perforated, transverse partitions, 
through which the liquid contents more or less freely 
pass. 



304 



HOW CROPS GROW. 



Milk Ducts. — Besides the ducts already described, 
there is, in many plants, a system of irregularly branched 
channels containing a milky juice (latex) as in the 
sweet potato, dande- _z^ 

lion, milk-weed, etc. 
These milk- ducts « 
occur in all parts of 
the plants, but most 
abundantly in the 
pith and inner bark 
of stems and in the 
cellular tissue of 
roots. They often so 
completely permeate 
all the organs of the 
plant that the slight- 
est wound breaks 
some of them and 
causes a flow of latex. 
The latter, like ani-// 
mal milk, is a watery 
fluid holding in sus- 
pension minute gran- 
ules or drops which ^^"o, 
make it opaque.^" 
The latex often con- 
tains the organic 
substances peculiar 
to the plant, acquires 
a sticky, viscid char- 
acter, and hardens 
on exposure to the air. Opium, India-rubber, gutta- 
percha, and various resins are dried latex. Alkaloids 
frequently occur, and ferments like papain (p. 104) are 
probably not uncommon in this secretion. 

Herbaceous Stems. — Annual stems of the exogenous 




Fis. 55. 



VEGETATIYE ORGANS OF PLANTS. 3Cu 

kind, whose growth is entirely arrested by winter, consist 
usually of a single ring of woody tissue with interior 
pith and suiTOunding bark. Often, however, the zone 
of wood is thin, and possesses but little solidity, while 
the chief part of the stem is made up of cell-tissue, so 
that the stem is herlaceous. 

Woody Stems. — Perennial exogenous stems consist, 
in temperate climates, of a series of rings or zones, cor- 
responding in number with that of the years during 
which their growth has been progressing. The stems of 
our shrubs and trees, especially after tlie first few years of 
growth, consist, for the most part, of woody tissue, the 
proportion of cell-tissne being very small. 

The annual cessation of growth which occurs at the 
approach of winter is marked by the formation of smaller 
or finer wood-cells, as shown in Fig. 54, e, while tha 
vigorous renewal of activity in the cambium at spring- 
time is exhibited by the growth of larger cells, and in 
many kinds of wood in the production of ducts, which, 
as in the oak, are visible to the eye at the interior of the 
annual layers. 

Sap-wood and Heart-wood. — The living processes 
in perennial stems, while proceeding with most force in 
the cambium, are not confined to that locality, but go on 
to a considerable depth in the wood. Except at the 
cambial layer, however, these jorocesses consist not in the 
formation of new cells, nor the enlargement of those 
once formed — not properly in growth — but in the trans- 
mission of sap and the deposition of organized matter on 
the interior of the wood-cells. In consequence of this 
deposition the inner or heart-wood of many of our forest 
trees becomes much denser in texture and more durable 
for industrial purposes. It then acquires a color differ- 
ent from the outer or sap-wood (alburnum), becomes 
brown in most cases, though it is yellow in the barberry 
and red in the red cedar. 
20 



30G now CROPS grow. 

The final result of the filling np of the cell of iho 
heart-wood is to make this part of the stem almost or 
quite impassable to sap, so that the interior wood may be 
removed by decay without disturbing the vigor of the 
tree. 

Passage of Sap through the Stem. — The stem, 
besides supporting the foliage, flowers and fruit, has also 
a most important office in admitting the passage upward 
to these organs of the water and mineral matters which 
enter the plant by the roots. Similarly, it allows the 
downward transfer to the roots of substances gathered 
by the foliage from the atmosphere. To this and other 
topics connected with the ascent and descent of the sap 
we shall hereafter recur. 

The stem constitutes the chief part by weight of many 
plants, esj)ccially of forest trees, and serves the most im- 
portant uses in agriculture, as well as in a thousand other 
industries. 

§ 3. 

LEAVES. 

These most important organs issue from the stem, are 
at first folded curiously together in the butl, and after- 
wards expand so as to present a great amount of surface 
to the air and light. 

The leaf consists of a thin membrane of cell-tissue 
directly connected with the cellular layei* of the bark, 
arranged upon a skeleton or net-work of fibers and ducts 
continuous with those of the inner bark and wood. 

In certain plants, as cactuses, there scarcely exist any 
leaves, or, if any occur, they do not differ, except in 
external form, from the stems. Many of these plants^ 
above ground, are in form all stem, while in structure 
and function they are all leaf. 

In the grasses, although the stem and leaf are distin- 



VEGETATIVE OTIGAN^P. OF PLANTS. 307 

guislial)lc in shape, they arc but little unlike in other 
external charaeters. 

In forest trees, we find the most obvious and striking 
differences between the stem and leaves. 

Color of Leaves. — A peculiarity most character- 
istic of the leaves of the higher orders of plants, so long 
as they are in vigorous discharge of their proper vegeta- 
tive activities, is the possession of a green color, due to 
the presence of Clilorojifiyl. (See p. 124.) This color 
is also proper in most cases to the young bark of the 
stem, a fact further indicating the connection between 
these parts, or rather demonstrating their identity of 
origin and function, for it is true, not only in the case 
of the cactuses, but. also in that of all other young 
plants, that the green (young) stems perform, to some 
extent, the same offices as tlie leaves, the latter being, in 
fact, growtlis from and extensions of the bark. 

The loss of green color that occurs in autumn, in the 
foliage of our deciduous trees, or on the maturing of the 
plant, as with the cereal grains, is related to the cessa- 
tion of growth and death of the leaf, and results from 
chemical changes in the chlorophyl-pigment. 

Plants naturally destitute of chlorophyl, like Indian 
pipe (3Io7iotropa), Dodder (Cuscuta), Mushrooms, 
Toadstools, and fungi generally, are parasites on living 
or dead organisms, from which they derive their nour- 
ishment. Such plants cannot construct organic sub- 
stances out of inorganic matters, as do the plants having 
chlorophyl. 

When leaves, ordinarily green, are totally excluded 
from light, or develop at a low temperature, they have a 
pale yellow color; on exposure to light and warmtli they 
become green. In both cases the C hIorophyI-gra?mIes 
are formed, hut the chlorophyl-pigment appears only in 
the latter. In absence of iron, leaves are white, contain 
no chlorophyl granules, and growth is arrested. 



308 HOW CROPS GROW. 

Tliere are many leafy plants cultivated for ornamental purposes 
with more or less brown, red, yellow, white, or variegated foliage, 
which are by no means destitute of chlorophyl, as is shown by micro- 
scopic examination, though this siibstance is associated with other 
coloring matters which mask its green tint. 

Structure of Leaves. — While in shape, size, modes 
of arrangement upon and attachment to tlie stem, we 
iiiid among leaves no end of diversity, there is great sim- 
plicity in the matter of their internal structure. 

The whole surface of the leaf, on both sides, is cov- 
ei'ed with epidermis, a coating which, in many cases, 
may be readily stripped off the leaf, and consists of thick- 
walled cells, which are, for the most part, devoid of liq- 
uid contents, except wdien very young. [E, E, Fig. 5G.) 

Fig. 50 represents the appearance of a bit of bean-leaf as seen on a 
section from the njiper to the loAver surface, and highly magnified. 

Below the upper epidermis, there ofjten occur one or 
more layers of oblong cells, whose sides are in close con- 
tact, and which are arranged endwise, with reference to 
the flat of the leaf. Below these, down to the lower- epi- 
dermis, for one-half to three-quarters of the thickness of 
tlie leaf, the cells are commonly spherical or irregular in 
figure and arrangement, and more loosely disposed, with 
numerous and large interspaces. 

The interspaces among the leaf-cells are occuj)ied with 
air, which is also, in most cases, the 
only content of the epidermal cells. 
,, . The interior cells of the leaf are filled 
tO \j\ with sap and contain the clilorophiil- 
(ifs?:'^-f^i4tV ^^'^^^^^'^^^^ Under the microscope, these 
'3jii-ii:lili ^1*6 commonlv seen attached to the walls 
n|iPtiM:IW of the ceils, as in Fig. 56, or coating 
SjS^fiWfe^ grains of starch, or else floating free in 
#i^^Sl° the cell-sap. 

The structure of the veins or ribs of 

the leaf is similar to that of the vascular 

Fii;. 5G bundles of the stem, of which they are 

branches. At «, Fig. 5G, is seen the cross section of a 

vein in the bean-leaf. 



VEGETATIVE ORGANS OF PLANTS. 



309 



The epidermis^ while often smooth, is frequently beset 
with hairs or glands, as seen in the figure. These are 
variously shaped cells, sometimes empty, sometimes, as 
in the nettle, filled with an irritating liquid. 

Leaf-Pores. — The epidermis of the mature leaf is pro- 
vided with a vast number of '" breathing pores," or stomata, 
by means of which the intercellular spaces in the interior 
of the leaf are brought into direct communication with 
the outer atmospiiere. Each of these stomata consists 
usually of two curved guard-cells, which are disposed 

toward each other like the 
halves of an elliptical car- 
riage-spring. (Figs. 52 and 
53.) The opening between 
them is an actual orifice in 
the skin of the leaf. The 
size of the orifice is, how- 
ever, constantly changing, 
as the atmosphere becomes 
drier or more moist, and as 
the sunlight acts more or 
less intensely on its surface. In strong light they curve 
outwards, and the aperture is enlarged ; in darkness they 
straighten and shut together, like the springs of a heavily- 
loaded carriage, and nearly or entirely close the entrance. 
The effect of water usually is to 
close their orifices. 

In Fig. 56 is represented a section^ 
tlirongh the shorter diameter of a pore' 
on the under surface of a bean-leaf. 
The air-space within it is shaded black. 
Unlike the other epidermal cells, those 
of the leaf -pores contain chlorophyll 
granules. 

Fig. 57 represents a portion of the epi- 
dermis of the upper surface of a potato- 
leaf, and Fig. 58 a similar portion of the 
under surface of the same leaf, magnified ^ 

200 diameters. In both figures are seen the open stomata between the 
semi-ellii)tical cells. The outlines of the other ei^idermal cells are 




Fig. 57. 




310 now CROPS GROW. 

marked by irregular d()ul)le lines. The round bodies In the guard- 
cells of the pores are stareii-grains, often present in tliese cells, when 
not existing in any other i>artof the leaf. 

The stomata are, with few exceptions, altogether want- 
ing on the submerged leaves of aquatic plants. On 
floating leaves they occur, but only on the upper surfacCo 
Thus, as a rule, they are not found in contact with 
liquid water. On the other hand, they are either absent 
from, or comparatively few in number upon, the upper 
surfaces of the foliage of land plants, wbicii are exposed 
to tlie heat of the sun, while they occur abundantly on 
the low^er sides of all green leaves. In number and size 
they vary remarkably. Some leaves possess but 800 to 
the square inch, while others have as many as 170,000 to 
that amount of surface. A])out 100,000 may be counted 
on an average-sized apple-leaf. In general, they are 
largest and most numerous on plants which belong to 
damp and shaded situations, and then exist on both sides 
of the leaf. 

Tlie epidermis itself is most dense — consists of thick- 
walled cells and several layers of them — in case of leaves 
which belong to the vegetation of sandy soils in liot cli- 
mates. Often it is impregnated with wax on its upper 
surface, and is thereby made almost impenetrable to 
moisture. On the other hand, in rapidly-growing plants 
adapted to moist situations, the epidermis is thin and 
delicate. 

Exhalation of Water-Vapor. — A considerable loss 
of water goes on from the leaves of growing plants when 
they are freely exposed to the atmosphere. The water 
thus lost exhales in the form of invisible vapor. The 
quantity of water exhaled from any plant may be easily 
ascertained, provided it is growing in a pot of glazed 
earthen or other impervious material. A metal or glass 
cover is cemented air-tight to the rim of the vessel, and 
around the stem of the plant. The cover has an open- 



VEGETATIVE OKGAl^S OE PLAi^TS. 311 

ing with a cork, through which weighed quantities of 
water are added from time to time, as required. Tlie 
amount of exhahition during any given interval of time 
is learned with a close approacli to accuracy by simply 
noting the loss of weight which the plant and pot 
together sufter. Hales, who first experimented in this 
manner, found that a vigorous sunflower, three and a 
half feet high, whose foliage had an aggregate surface of 
39 square feet, gave off 30 ounces av. of water in a space 
of 12 hours, during a very warm, dry day. The average 
*^rate of perspiration" for 15 days, in July and August, 
was 20 ounces av. At night, with "any sensible, though 
small dew, the perspiration was nothing." Knop 
observed a maize-plant to exhale, between May 22d and 
September 4th, no less than 3G times its weight of water. 
Hellriegel (at Dahme, Prussia) found that summer 
wheat and rye, oats, beans, peas, buckwheat, red clover, 
yellow lupine and summer colza, on the average exhaled 
300 grams of water for 1 gram of dry matter produced 
above ground, during the entire season of growth, when 
stationed in a sandy soil. {Die Mctliode dcr SandktiUur, 
p. GG2.) 

Exhalation is not a regular or uniform process, but 
varies with a number of circumstances and conditions. 
It depends largely upon the dryness and temperature of 
the air. When the air is in the state most favorable to 
evaporation, the loss from the plant is ra})id and large. 
When the air is l(»aded witli moisture, as during dewy 
nights ur rainy weather, then exhalation is nearly or 
totally checked. 

Tlie temperature of the soil, and even its chemical 

composition, the condition of the leaf as to its texture, 

age, and number of stomata, likewise affect the rate of 

exhalation. 

^"J^ ^ Exhalation is rather incidental than necessary to the 

Mife of many ])lants, since it may be suppressed or reduced 



312 



HOW CROPS GROW. 



to a minimum, as in a Wardian case or fernery, without 
evident influence on grovvtii ; but plants of parentage 
naturally accustomed to copious exlialation of water 
flourish best where the conditions are favorable to this 
process. Exhalation is not injurious, unless the loss 
be greater than the supply. If water escapes from the 
leaves faster than it enters the roots, the succulent organs 
soon wilt, and if this disturbance 
goes on too far the plant dies. 

Exhalation ordinarily proceeds to 
a large extent from the surface of 
the epidermal cells. Although the 
cavities of these cells are chiefly oc- 
cupied with air, their thickened walls 
transmit outward the water which is 
supplied to the interior of the leaf. 
Otherwise the escape of va^^or occurs 
through the stomata. These pores 
appear to have the function of facil- 
itating exhalation, by their property 
of opening when exposed to sunlight. 
Thus evaporation from the leaves is 
favored at the time when root-action 
is most vigorous, and the plant is to 
the greatest degree surcharged with 
water. 

Access of Air to the Interior 
of the Plant.— Not only does the Fi- 59. 

leaf allow the escape of vapor of water, but it admits of 
the entrance and exit of gaseous bodies. 

The particles of atmosi)heric air have easy access to 
the interior of all leaves, however dense and close their 
epidermis may be, how^ever few or small their stomata. 
All leaves are actively engaged in absorbing or exhaling 
certain gaseous ingredients of the atmosphere during 
the whole of their healthy existence. 




IIEPRODUCTIVE ORGANS OF PLANTS. 313 

The entire plant is, often, pervious to air through 
tlie stomata of the leaves. These communicate with the 
intercellular spaces of the leaf, which are, in general, 
occupied exclusively with air, and these again connect 
with the ducts which ramify throughout the veins of the 
leaf and branch from the vascular bundles of the stem. 
In the bark or epidermis of woody stems, as Hales long 
ago discovered, pores or cracks exist, through whicli 
the air has communication with the longitudinal ducts. 

These facts admit of demonstration by simi^le nieans. Saclis employs 
for this purpose an apparatus consisting of a short, wide tube of glass, 
B, Fig. 59, to which is adapted, below, by a tightly-fitting cork, a bent 
glass tube. The stem of a leaf is passed through a cork which is then 
secured air-tight in the other opening of the wide tube, the leaf itself 
being included in the latter, and the joints are made air-tight by smear- 
ing with tallow. The whole is then placed in a glass jar containing 
enough water to cover the projecting leaf -stem, and mercury is quickly 
poured into the open end of the bent tube, so as nearly to fill the lat 
ter. The pressure of the column of this dense liquid immediately 
forces air into the stomata of the leaf, and a corresponding quantity is 
forced on through the intercellular spaces and through the vein ducts 
into the ducts of the leaf -stem, whence it issues in fine bubbles at S. 
It is even easy in many cases to demonstrate the permeability of the 
leaf to air by immersing it in water, and, taking the leaf -stem between 
the lips, produce a current by blowing. In this case the air escapes 
I'rom the stomata. 

The air-passages of the stem may be shown by a similar arrange- 
ment, or in many instances, as, for example, with a stalk of maize, by 
simply immersing one end in water and blowing into the other. 

On the contrary, ro^tsare destitute of any visible 
external pores, and are not pervious to air or vapor in 
the sense that leaves and young stems are. 

The air passages in the plant correspond roughly to 
the mouth, throat, and breathing cavities of the animal. 
We have, as yet, merely noticed the direct communica- 
tion of these passages with the external air by means of 
microscopically visible openings. But the cells which 
are not visibly porous readily allow the access and egress 
of water and of gases by osmose. To the mode in which 
this is effected we shall recur on subsequent pages. 

The Offices of Foliage are to put the plant in com- 
munication with the atmos2)here and with the sun. Od 



314 now ciiops geow. 

the one hand it permits, and to a certain degree facili- 
tates, the escape of the water which is continually 
pumped into the phmt by its roots, and on the other 
hand it absorbs, from the air that freely penetrates it, 
certain gases which furnish the principal materials for 
the construction of vegetable matter. We have seen that 
the plant consists of elements, some of which are volatile 
at the lieat of ordinary fires, while others are fixed at 
this temperature. When a plant is burned, the former, 
to the extent of 90 to 99 per cent of the plant, are con- 
verted into gases, the latter remain as ashes. 

The reorganization of vegetation from the products of 
its combustion (or decay) is, in its simplest phase, the 
gathering by a new plant of the ashes from the soil 
through its roots, and of these gases from the air by its 
leaves, and the compounding of these comparatively sim- 
ple substances into the higlily complex ingredients of the 
vegetable organism. Of this work the leaves have by 
far the larger share to perform ; hence the extent of 
their surface and their indispensability to the welfare of 
the plant. 



CHAPTER IV. 
reproductive' OKGANS OF PLANTS. 

§ 1. 

MODES OF EEPKODUCTIO:!^. 

Plants are reproduced in various ways. The simplest 
cellular j)lants have no evident special organs of repro- 
duction, but propagate themselves solely by a process of 
division which begins in the protoplasm, as already de- 
scribed in case of Yeast, p. 253. The lower so-called 
flowerless plants {Cryptogams), including molds, blights, 
mildews, mushrooms, toadstools (Fungi), mosses, lichens, 



REPRODUCTIVE ORGANS OF RLANTS. 315 

etc., reproduce themselves in part by spores, each of 
which is a single minute cell that is capable of develop- 
ing into a plant like that from which it was thrown off. 

In very many cases a portion or ^^ cutting " of root, 
stem or leaf, from herb or tree, placed in moist, warm 
earth, will grow and develop into a new plant in all 
respects similar to the original. The potato, grape, 
banana, and sugar-cane plants are almost exclusively 
propagated in this manner. In budding and grafting a 
l)ortion of stem, carrying a single bud or a number of 
buds (scion), is planted, not in the soil, but in the cam- 
bial layer of a living root or stem with which it unites 
and thenceforward grows. 

The higher orders of plants {Phanerofjams) have spe- 
cial reproductive organs, constituting or contained in 
theiv flowers, whose office it is to produce seed, the essen- 
tial part of which is the embryo, a ready-formed minia- 
ture plant which may grow into the full likeness of its 
parent. 

§ 2- 

THE FLOWER. 

In the higher plants the onward growth of the stem or 
of its branches is not necessarily limited, until from the 
tei'ininal buds, instead of leaves, only flowers unfold. 
When this happens, as is the case with most annual and 
biennial plants, raised on the farm or in the garden, the 
vegetative energy has usually attained its fullest develop- 
ment, and the reproductive function begins to prepare 
for the death of the individual by providing seeds which 
shall perpetuate the species. 

There is often at first no apparent diiforence between 
the leaf-buds and flower-buds, but commonly, in the later 
stages of their growth, the latter are to be readily dis- 
tinguished from the former by their greater size, and by 
peculiar shape or color. 



316 



HCW CROPS GROW. 



The Flower is a short branch, bearing a collection of 
organs, which, though usually having little resemblance 
to foliage, mtiy be considered as jeaves, more or less mod- 
ified in form, color, and office.^ 

The flower commonly presents four different sets of 
organs, viz.. Calyx, Corolla, Stamens, and Pistils, and is 
then said to be complete, as in case of the apple, potato, 
and many common plants. Fig. 60 represents the com- 
plete flower of the Fuchsia, or ladies' ear-drop, now uni- 
versally cultivated. In Fig. 61 the same is shown in 
section. 

The Calyx (cup) ex, is the outermost floral envelope. 
Its color is red or white in the Fuchsia, though generally 
it is green. When it consists of several distinct leaves, 

they are called 

sepals. The calyx 

is frecpiently small 

a n d inconspicu- 

ouf. In some 

cases it falls away 

as the flower 

o j> ens. I n t h c 

Fuclisia it firmly 

adheres at its base 

t3 the seed-vessel, 

and is divided into 

four lobes. 

The Corolla 

(crown), c, or ca, 

is one or several 

series of leaves 

which are situated 
within the calyx. It is usually of some other than a 
green color (in the Fuchsia, purple, etc.), often has 
marked i)ecuiiaritios of form and great delicacy of struc- 
ture, and thus chiefly gives beauty to the flower. When 





Tig. eo. 



Fi"-. 61. 



REPKODUCTIVE ORGAN'S OF PLANTS. 317 

the corolla is divided into separate leaves, these are 
termed petals. The Fuchsia has four petals, which are 
attached to the calyx-tube. 

The Stamens, s, in Figs. 60 and 61, are generally 
slender, thread-like organs, terminated by an oblong 
sack, the nether, which, when the flower attains its full 
growth, discharges a fine yellow or brown dust, the so- 
called pollen. 

The anthers, asweU as the grains of poHen, vary in form witli nearly 
every kind of plant. The yellow pollen of Tine and Siniice is not in- 
fretpiently transi^orted by the wind to a great distance, and when 
brought down by rain in considerable quantities, lias been niistalvcn 
for sulphur. 

The Pistil, p, in Figs. 60 and 61, or pistils, occupy 
the center of the perfect flower. They are exceedingly 
various in form, but always have at their base the seed- 
vessels, or ovaries, ov, in which are found the ovules or 
rudimentary seeds. The summit of the pistil is desti- 
tute of the epidermis which covers all other parts of the 
plant, and is termed the stigma, st. 

As has been remarked, the floral organs may be consid- 
ered to be modified leaves ; or rather, all the appendages 
of the stem — the leaves and the parts of the flower to- 
gether — are different developments of one fundamental 
structure. 

The justness of this idea is sustained by the transform- 
ations which are often observed. 

The Rose in its natural state has a corolla consistins: 
of five })etals, but has a multitude of stamens and pistils. 
In a rich soil, or as the effect of those agencies which aro 
united in'^ cultivation," nearly all the stamens lose their 
reproductive function and proper structure, and revert 
to petals ; the flower becoming '''double." The tulip, 
poppy? cind numerous garden-flowers, illustrate this in- 
teresting metamorpliosis, and in these flowers we may 
often see the various stages intermediate between the 
perfect petal and the unaltered stamen. 



318 now CROPS GROW. 

On the other hr.nd, the reversion of all the floral 
organs into ordinary green leaves has been observed not 
infrequently, in case of the rose, white clover, and other 
plants. 

While the complete flower consists of the four sets of 
organs above described, only the stamens and pistils are 
essential to the production of seed. The latter, accord- 
ingly, constitute a perfect flower, even in the absence of 
calyx and corolla. 

The flower of buckwheat has no corolla, but a white or 
pinkish calyx. 

The srasses have floAvers in which calyx and corolla are 
represented by scale-like leaves, which, as the plants ma- 
ture, become chaff. 

In various plants the stamens and pistils are borne on 
separate flowers. Such are called monmcio^is plants, of 
which the birch and oak, maize, melon, srpiash, encum- 
ber, and often the strawberry, are examples. 

In case of maize, the staminate flowers are the " tas- 
sels "at the summit of the stalk; the pistillate flowers 
are the young ears, the pistils themselves being the 
" silk," each fiber of which has an ovary at its base, that, 
if fertilized, develops to a kernel. 

Dimciotis plants are those which l)ear the staminate 
(male, or sterile) flowers and the i)istillate (female, or 
fertile) flowers on different individuals ; the willow, the 
hop-vine, and hemp, are of this kind. 

Nectaries are special organs — glands or tubes — secret- 
ing a sugary juice or nectar, which serves as food to 
insects. The clovers and honeysuckles furnish familiar 
examples. 

Fertilization and Fructification. — The grand func- 
tion of the flower is fnictification. For this purpose 
pollen must fall upon or be carried by wind, insects, or 
other agencies, to the naked tip of the pistil. Thus sit- 
uated, each pollen-grain sends out a slender microscopic 



REPRODUCTIVE ORGANS OF PLANTS. 



319 



tube which penetrates the intei'ior of the pistil until it 
enters the seed-vessel iind comes m contact with tiic ovule 
or rudimentary seed. This contact being established, 
the ovule is fertilized and begins to grow. Thencefor- 
ward the corolla and stamens usually wither, while the 
base of the pistil and the included ovules rapidly increase 
in size until the seeds are ripe, when the seed-vessel falls 
to the ground or else opens and releases its contents. 

Fig, G2 exhibits the process of fertilization as observed 
in a plant allied to buckwheat, viz., the Polygormm con- 
volvulus. The cut represents a magnified section length- 
wise through the short pistil ; a is the stigma or summit 
of the pistil ; b are grains of pollen ; 
c are pollen tubes that have penetrated 
into the seed-vessel which forms the 
base of tlie pistil ; one has entered the 
mouth of the rudimentary seed, g, and 
reached the embryo sack, e, within 
which it causes the development of a 
germ ; d represents the interior wall 
of the seed-vessel ; A, the base of the 
seed and its attachment to the seed- 
vessel. 

Self-Fertilization occurs when 
ovules are impregnated by pollen 
from the same flower. In many plants 
self-fertilization is favored by the posi- 
tion of the organs concerned. In the 
pendent flower of the Fuchsia as well 
as in the upright one of the strawberry the stigma is just 
below and surrounded by the anthers, so that when the 
mature pollen is discharged it cannot fail to fall upon the 
stigma. Some flowers, as those of the closed gentian 
{Gentiana Andrewsii) and the small subterranean blos- 
soms of sheep-sorrel (Oxalis acetosella), touch-me-not 
{Impatiens) , and of many violets, never open, and not 




Fig. 62. 



320 HOW CROPS GROW. 

only are self-fertile but cannot well be otherwise. Some 
plants which carry these closed and inconspicuous subter- 
ranean flowers depend upon tliem for reproduction by 
seed^ their large and showy serial flowers being often bar- 
ren, as in violets, or totally infertile ( Voandzeia.) Flax 
and turnips are self-fertilizing. 

Cross-Fertilization results from the contact of the 
pollen of one flower with the ovules of another. In many 
j^lants remarkable arrangem.ents exist that hinder or 
totally prevent self-fertilization and favor or ensure cross- 
fertilization. 

In monmcious plants, as hazel oi' squash, flowers of one 
sort yield pollen, others, different, contain the ovules ; 
so that two distmct and more or less distant blossoms of 
tiie same plant are necessary for seed-production. 

In the dimcious poplar and hops, the plant that pro- 
duces pollen never carries ovules and that which bears the 
latter is destitute of the former, so that two distinct 
plants must co-operate to form seeds. 

It often happens that the pollen of a flower cannot fer- 
tilize the ovules of the same flower. This may be eitlier 
because the stigma is behind the pollen in development, 
as in case of various species of geranium, or because the 
stigma has passed its receptive period before the pollen is 
mature, as in Sweet Vernal Grass (Anthoxanthum odo- 
ratum). In both instances the ripened pollen may reach 
stigmas that are ready in other flowers and fertilize their 
ovules, insects being often the means of transportation. 

In a large number of flowers, whose pollen and stigmas 
are simultaneously prepared, the position of the organs 
is such that self-fertilization is difficult or im2:)ossible. 
The Iris, Crocus, Pansy, Milk-weed (AsrJepias), and many 
Orchids, are of this class. The offices of insects in search 
of nectar, or attracted by odors, are here indispensable. 
The common red clover cannot produce seed witliout 
insect aid, and the bumblebee customarily performs this 



KEPRODUCTIYE ORGANS OF PLANTS. 321 

service. The insect, in exploring a flower for nectar, 
leaves upon its stigma pollen taken from the flower last 
visited, and in emerging renews its burden of pollen to 
bestow it in turn upon the stigma of a third flower. 

Cross-fertilization is doubtless often elfectcd by insects 
in case of flowers which are in all respects adapted for 
self-fertilization, while flowers that casual examination 
would pronounce self-fertile are in fact of themselves 
sterile. The flowers of rye open singly, the long stamens 
shortly mature and discharge their pollen, which falls on 
the stigmas of flowers standing lower in the same head, 
or on neighboring heads. According to Rimepare, the 
individual rye-flower can fertilize neither itself nor the 
different flowers of an ear, nor can the different ears of 
one and the same plant pollinate one anotlier with suc- 
cess, although no mechanical hindrance exists. (Sachs, 
Physiology of Plants, p. 71)0.) 

Results of Self-Fertilization and Cross-Fertili- 
zation. — Sprengel, one of the early students of Plant- 
Reproduction, wrote in 1793, '^ Nature appears to be 
unwilling that any flower shall be fertilized by its own 
pollen." Extenc-ive observation indicates decidedly 
that cross-fertilization is far more general than self- 
fertilization, especially among the higher plants. Dar- 
win has shown that, in many cases, the pollen of a flower 
is incaj^able of fertilizing its own ovules, and that the 
pollen from another flower of the same plant is scarcely 
more potent. In these cases the pollen from a flower 
borne by another plant of the same kind is potent, and 
the more so the more unlike the two plants are. 

In Darwin's trials on the reproduction of the Morning 
Glory, Ipowca purpurea, cnrried out through ten gener- 
ations, the average height of 73 self-fertilized plants was 
6G inches, while that of the same number of crossed 
plants was 85.8 inches, or in the ratio of 77 to 100. 
The relative number of seeds produced by the self-fertil- 
21 



322 now CROPS grow. 

izod and cross-fertilized plants in the 1st, 3d, and 9tli 
generations were respectively as G4 to 100; 35 to 100, 
and 2G to 100. 

In otlier cases, but, so far as observed, much less com- 
monly, self-fertilization gives the best results both as 
regards numbers and vigor of offspring. In Darwin's ex= 
13eriments a variety of Mimulits lateus originated, of 
Avhich the sclf-i'ertilized progeny surpassed the cross-fer- 
tihzed, during several generations. In the seventh gen- 
eration the ratio of superiority of the self-fertilized, as 
regards numbers of fruit, was as 137 to 100;, and m respect 
to size of plants as 12 G to 100. 

Continued self-fertilization, is thus limited by its ten- 
dency, as statistically determined, to reduce both the 
vegetative and reproductive vigor of the plant. On tlie 
other hand, cross- fertilization is possible or practicable 
only within very narrow bounds, and the increased pro- 
ductiveness that follows it soon reaches a limit, as is 
shown by the history of vegetable hybrids. 

That neither mode of fertilization is exclusively or speci- 
ally adapted to the highest development of plants in gen- 
eral, or of particular kinds of plants, is shown by the fact 
that in the course of Darwin's researches on the Ipomea 
purpurea, just referred to, in the sixth generation a self- 
fertilized plant (variety) appeared, which was superior to 
its cros'sed collateral, and was able to transmit its vigor 
and fertility to its descendants. 

It is evident, therefore, that the causes which lead to 
higher development co-operate most fully, sometimes in 
the one, sometimes in the other, mode of impregnation 
and do not necessarily belong to cither. We must be- 
lieve that excellence in offspring is the result of excel- 
lence in tlie parents, no matter what lines their heredity 
may have followed, except as these lines have influenced 
their individual excellence. That crossing commonly 
gives better oifspring than in-and-in breeding is due to 



REPRODUCTIVE ORGANS OF PLANTS. 323 

the fjict tliat in the latter both parents arc likely to pos- 
sess by inheritance the same imperfections, which are 
thns intensified in the progeny, while in cross-breeding 
the parents more usually have diiiercnt imperfections 
which often, more or less, compensate each other in the 
immediate descendants. 

Hybridizing. — As the sexual union of quite different 
kinds of animals sometimes results in the birth of a 
hybrid, so, among plants, the ovules of one kind (spe- 
cies, or even genus) may be fertilized by the pollen of 
another different kind, and the seed thus developed, in 
its growth produces a hybrid plant. As in the animal, 
so in the vegetable kingdom, the range within which 
hybridization is possible appears to be very narrow. It 
is only betv/een rather closely allied plants that fecunda- 
tion can take place, and the more close the resemblance 
the more ready and fruitful the result. Wheat, rye, 
and barley, in ordinary cultivation, show no tendency to 
"mix ;" tlie pollen of one of these similar plants rarely 
fertilizino:* the ovules of the others. But external sim- 
ilarity is no certain mark of capacity for hybridization. 
The apple and pear have never yet been crossed, while 
the almond and nectarine readily form hybrids. (Sachs. ) 

Hybrids are usually less productive of seeds than the 
parent plants, and sometimes are entirely sterile, but, on 
the otlier hand, they are often more vigorous in their 
vegetative development — produce larger and more numer- 
ous leaves, flowers, roots, and shoots, and are longer- 



*In the first edition was written, "beinp: incapnhle of fertilizing." 
The experiments of Mr. Carman liave lately shown that wheat and 
rye may be made to produee fertile hybrids. A beardless wheat was 
fertilized by rye-pollen and prodnced nine seeds, eight of which Avere 
fully fertile, one nearly sterile. The last yielded 20 heads, whicli bore 
only a few grains. Tlie plants from the nine fertUe seeds Avcrc i5olli- 
nated again with rye and prodnced but a few f cn-tile seeds. A few 
plants, seven-eigliths rye, wcue finally ]no<hu'ed, which were, however, 
totally sterile. Of the three-fourths "cross, fertile progeny has been 
raised for several years, and the characters of this genns-hybrid ap- 
pear to be nearly fixed, though occasionally a sterile head appears.— 



S 



ural New Yorker, 1883, p. G44. 



324 HOW CROPS GROW. 

lived than their progenitors. For tliis reason hybrids 
are much valued in fruit- and flower-culture. 

Some genera of plants have great capacity for produc- 
ing hybrids. The Vine and the Willow are striking 
examples. The cultivated Vine of Earope and Western 
Asia is Vitis vinifera. In the United States some 
twelve distinct species are found, of which three, Vitis 
riparia, Vitis cBstivalis, and Vitis lahniaca, are native to 
New England. Nearly all these kinds of grape cross 
with such readiness that scores of new hybrids have been 
brought into cultivation. "The kinds now known as 
Clinton, Taylor, Elvira, Franklin, are hybrids of V. 
riparia and V. lahrusca. York-Madeira, Eumelan, 
Alvey, Morton's Virginia, Cynthiana, are crosses of V, 
labrusca and V. mstivalis. Delaware is a hybrid of V. 
labruscay V. vinifera, and V. cBdivalis. Ilerbemont, 
Ilulander, and Cunningham are hybrids of V. cBstivalis, 
V. ci7icrea, and V. vinifera. Tlie vine known in France 
as *^Gaston-Bazille" is a hybrid of V. Icihrusca, V. cesti- 
valis, V. rupestris, and V. ri])aria.^'* The foregoing 
are "spontaneous wild hybiidi^." The "Rogers Seed- 
lings," including Salem, Wilder, Barry, Agawam, Mas- 
iasoit, etc., are examples of artificial hybrids of F. vi7i- 
if era and V. lahrusca. 

Hybridization between plants is effected, if at all, by 
removing from the flower of one kind the stamens 
before they shed their pollen, and dusting the summit 
of the properly-matured jnstil with pollen from another 
kind. Commonly, when two plants hybridize, the pollen 
of either will fertilize the ovules of the other. In some 
cases, however, two plants yield hybrids by only one 
order of connection. 

Tlie mixing of different Varieties, as commonly hap- 
pens among maize, melons, etc., is not hybridization, 



*Minardet in Saclis's Lectures on the Physiolorjy of Plants, 1887, p. 785. 



REPRODUCTIVE ORGANS OE PLANTS. 325 

in the long-established sense of this word, but rather 
*^ cross-breeding." The two processes are, however, fun- 
damentally the same, and their results are sufficiently 
distinguished by the terms Species-hybrid, or Genus- 
hybrid, and Variety-hybrid. We are thus led to brief 
notice of the meaning of the terms Species and Vari- 
ety, and of the distinctions employed in Botanical 
CJassification. 

Species. — Until recently naturalists generally held 
the view that in ^' the beginning" certain kinds of plants 
and animals were separately created, with the power to 
reproduce their own kind, but incapable of fertile hybrid- 
ization, so that only such original kinds could be per- 
petuated. Such supposed original kinds were called 
Species. At present, on the contrary, most biologists 
regard all existing kinds of plants and animals as prob- 
ably the results of a very slow and gradual development 
or evolution from one vastly remote ancestor of the sim- 
plest type. On this view a Plant-Species comprises a 
number of individuals, "among which wo are unable to 
distinguish greater differences tnan experience shows us 
we should find among a number of plants raised from 
the seed of the same parent." 

On the former view, plants yielding fertile hybrids or 
crosses must be Varieties of the same species. On the 
latter view different Species may hybridize. They are 
not originally different, and by Evolution or Reversion 
may pass into each other. On either view, the distinc- 
tion of plants into species is practically the same, being 
largely a matter of expert judgment or agreement among 
authorities, and not capable of exact decision by refer- 
ence to fixed rules or known natural laws. The charac- 
ters that are taken to be common to all the individuals 
of a species are termed specific cliarcicters. The differ- 
ences used to divide plants into species are called specific 
differe7ices. 



326 now CROPS grow. 

Naturalists, acting -under the older view, attempted to 
draw specific characters more finely than is now thouoht 
practicable. Many plants formerly described as separate 
species are now united together into a single species, 
the various forms at first supposed to be specifically or 
originally distinct having been shown to be of common 
origin, either by producing them from each other or by 
observing that they were connected through a series of 
intermediate forms, insensibly grading into each other. 

Varieties. — The individuals of any ''^species" dilfer. 
In fact, no two individuals are quite alike. Circum- 
stances of climate, soil, and situation increase these dif- 
ferences, and varieties originate when such differences 
are inherited and in tlie progeny assume a comparative 
permaiLe7ice. But as external conditions cause variation 
away from any particular representative of a species, so 
they may cause variation back again to the original type. 

Varieties most commonly originate in propagation by 
seed, especially in case of the trees or plants commonly 
cultivated for their fruit. Seedling grapes, apples, or 
potatoes are very likely to differ from their parents. 
Seed which has been imperfectly ripened or long kept is 
said to be prone to yield new varieties. 

Less frequently variations arise in propagation by 
cuttings, buds, grafts, or tubers. Pinks and Pelargo- 
niums in the florist's hands are prolific of these ^^ sports." 

The causes that produce varieties are probably numer- 
ous, but in many cases their nature and their mode of 
action is obscure or unknown. Scarcity or abundance 
of nutriment, we can easily comprehend, may, on the one 
hand, dwarf a plant, or, on the other, lead to the pro- 
duction of a giant individual ; but how, in some cases, 
the peculiarities thus impressed upon individuals become 
fixed, and are transmitted to subsequent generations, 
while in others they disappear, is difficult to explain. 
Varieties may often be perpetuated for a long time by 



REPRODUCTIVE ORGAIs^S OF PLANTS. 327 

the seed. This is true of our ccrcul and leguminous 
plants, which commonly reproduce their kind with strik- 
ing regularity. Varieties of some plants cannot, with 
certainty, be reproduced unaltered by the seed, but are 
continued in the possession of their peculiarities by cut- 
tings, layers, and grafts. The fact that the seeds of a 
potato, a grape, an apple, or pear cannot be depended 
upon to re])roduce the variety, may perhaps be more 
commonly due to unavoidable contact of pollen from 
other varieties (variety-hybridization) tlian to inability 
of the mother plant to perpetuate its peculiarities. 
That such inability often exists is, however, well estab- 
lished, and is, in general, most obvious in case of varie- 
ties that have, to the greatest degree, departed from the 
original specific type and of course, in sterile hybrids. 

The sports which originate in the processes of propa- 
gating from buds (grafts, tubers, cuttings) are perpet- 
uated by the same processes. 

Species and Varieties, as established in our botanical 
literature, are exemplitied by the Vine, whose species 'are 
vmifera, riparia^ lahrusca, etc., and some of whose 
North American Varieties, the results of hybridization, 
have already been enumerated. 

Genus (plural Genera). — Species which resemble 
each other in most important points of structure are 
grouped together by botanists into a genus. Thus the 
various species of oaks, — :white, red, black, scrub, live, 
etc., — taken together, form the Oak-genus Quercus, 
wliich has a series of characters common to all oaks 
(generic characters), that distinguishes them from every 
other kind of tree or plant. 

Families, or Orders, in botanical language, are 
groups of genera that agree in certain particulars. Thus 
the several plants well-known as mallows, hollyhock, 
okra, and cotton, are representatives of as many different 
genera. They all agree in a number uf points, especially 



328 HOW CROPS GROW. 

as regards the structure of their fruit. They are accord- 
ingly grouped together into a natural family or order, 
which differs from all others. 

Classes, Series, and Classification. — Classes are 
groups of orders, and Series are groups of classes. In 
botanical classification, as now universally employed — 
classification after the Natural System — all plants are 
separated into two series, as follows : 

1. Floivering Plants {Phanerogams), which produce 
flowers and seeds with embryos, and 

2. Floiverless Plants (Cryptogams), that have no 
proper flowers nor seeds, and are reproduced, in part, 
by spores which are in most cases single cells. This 
series includes Ferns, Horse-tails, Mosses, Liverworts, 
Lichens, Sea-weeds, Mushrooms, and Molds. 

It was beUevert, until recently, that there exists a sharp and abso- 
lute distinction between floAvering and llowerless plants, but our 
larger knowledge now recognizes that here, as among genera, species, 
and varieties, kinds merge or shade into each other. 

The use of Classification is to give precision to our 
notions and distinctions, and to facilitate the using and 
ac(juisition of knowledge. Series, classes, orders, genera, 
species, and varieties are as valuable to the naturalist as 
pigeon-holes are to the accountant, or slielves and draw- 
ers to the merchant. 

Botanical Nomenclature. — The Latin or Greek 
names which botanists employ are essential for the dis- 
crimination of plants, being equally received in all coun- 
tries, and belonging to all languages where science has a 
home. They are made necessary, not only by the confu- 
sion of tongues, but by confusions in each vernacular. 

Botanical usage requires for each plant two names, 
one to specify the genus, another to indicate the species. 
Thus all oaks are designated by the Latin word Quercus, 
while the red oak is Quercus ruhra, the white oak is 
Quercus alba, the live oak is Quercus vircus, etc. 



REPRODUCTIVE ORGANS OF PLANTS. 329 

The designation of certain important families of plants 
is derived from a peculiarity in the form or arrangement 
of the flower. Thus the pulse family, comprising the 
bean, pea, and vetch, as well as alfalfa and clover, are 
called Pcqnlionaceous plants, from the resemblance of 
their flowers to a butterfly (Latin, papilio). Again, the 
mustard family, including the radish, turnip, cabbage, 
water-cress, etc., are termed Cruciferous plants, because 
their flowers have four petals arranged like the four arms 
of a cross (Latin, crux). 

The flowers of a large natural order of plants are 
arranged side by side, often in great numbers, on the 
expanded extremity of the flower stem. Examples arc 
the thistle, dandelion, sunflower, artichoke, China-aster, 
etc., which, from bearing such compound heads, are 
called Composite plants. 

The Coniferous (cone-bearing) plants comprise the 
pines, spruces, larches, hemlocks, etc., whose flowers are 
arranged in conical receptacles. 

The flowers of the carrot, parsnip, and caraway are 
stationed at the extremities of stalks which radiate from 
a central stem like the arms of an umbrella ; hence they 
are called Umltelliferous plants (from umhel, Latin for 
little screen). 

§2. 

THE FRUIT. 

The FiiUiT compiises the seed-vessel and the seeds, to- 
gether with their various appendages. 

Fruits are either dehiscent when the seed-vessel opens 
and sheds the seed or are indehiscent when it remains 
closed. 

The seed-vessel, consisting of the base of the pistil in 
its matured state, exhibits a great variety of forms and 
characters, which serve, chiefly, to define the diifcrcnt 



330 HOW CROPS GROW. 

kinds of Fruits. Of these we shall only adduce such as 
are of common occurrence and belong to the farm. 

The Nut has a hard, leathery or bony in dehiscent 
shell, that usually contains a single seed. Examples are 
the acorn, chestnut, beech-nut, and hazel-nut. The cup 
of the acorn and the bur or shuck of the others is a sort 
of fleshy calyx. 

The Stone-fruit, or Drupe, is a nut enveloped by a 
fleshy or leathery coating, like the peach, cherry, and 
plum, also the butternut and hickory-nut. Easpberries 
and hhickbcrries are clusters of small drupes. 

Pome is a term applied to fruits like the apple and 
pear, the core of which is the true seed-vessel, originally 
belonging to the pistil, while the often edible flesh is the 
enormously enlarged and thickened calyx, whose with- 
ered tips are always to be found at the end opposite the 
stem. 

The Berry is a many-seeded fruit of which the entire 
seed-vessel becomes thick and soft, as the grape, currant, 
tonuito, and huckleberry. 

Gourd fruits have externally a hard rind, but are 
llcshy in the interior. The melon, squash, and cucum- 
ber are of this kind. 

The Akene is a fruit containing a single seed which 
docs not separate from its dry envelo]^. The so-called 
seeds of the composite plants — for eximiple, the sunflower, 
thistle, and dandelion — are akenes. On removing the 
outer husk or seed-vessel we find within the true seed. 
Many akenes are furnished with a 2^ap2)us, a downy or 
hairy appendage, the remains of the calyx, as seen in the 
thistle, which enables the seed to float and be carried 
about in the wind. The fruit or grain of buckwheat is 
akene-hke. 

The Grains are properly fruits. Wheat, rye, and 
maize consist of the seed and the seed-vessel closely 
united. When these grains are ground, the bran that 



REPRODUCTIVE ORGANS OF PLANTS. 331 

comes oil is the seed-vessel together with the outer coat- 
ings of the seed. Barley-grain, in addition to the seed- 
vessel, has the petals of the flower or inner chaff, and 
oats have, besides these, the calyx or outer chaff adher- 
ing to the seed. 

Pod is the name properly applied to any dry seed-ves- 
sel which opens and scatters its seeds when ripe. Sev- 
eral kinds have received special designations ; of these 
we need only notice one. 

The Legume is a pod, like that of the bean, which 
splits into two halves, along whose inner edges seeds are 
borne. The pulse family, or papilionaceous plants, are 
also termed legumhious, from the form of their fruit. 

The Seed, or ripened ovule, is borne on a stalk which 
connects it with the seed-vessel. Through this stalk it 
is supplied with nutriment while growing. When ma- 
tured and detached, a scai' commonly indicates the point 
of former connection. 

The seed has usually two distinct coats or integuments. 
The outer one is often hard, and is generally smooth. 
In the case of cot ton -seed it is covered with the valuable 
cotton fiber. The second coat is commonly thin and 
delicate. 

The Kernel lies within the integuments. In many 
cases it consists exclusively of the emhryo, or rudimen- 
tary plant. In others it contains, besides the embryo, 
what has received the name of endosperm. 

The Endosperm forms the chief bulk of all the 
grains. If we cut a seed of maize in two lengthwise, we 
observe, extending from the point where it was attached 
to the cob, the soft "chit," h, Fig. G3, which is the em- 
bryo, to be presently noticed. The remainder of the 
kernel, a, is endosperm ; the latter, therefore, yields in 
great part the flour or meal which is so important a part 
of the food of man and animals. 

The endosperm is intended for the support of the 



now CROPS GROW. 



yonng plant as it develops from the embryo, before it is 
caj^able of depending on the soil and atmosphere for sus- 
tenance. It is not, however, an indispensable part of the 
seed, and may be entirely removed from it, without 
thereby preventing the growth of a new plant. 

The Embryo, or Germ, is the essential and most 
important 2)ortion of the seed. It is, in fact, a ready- 
formed plant in miniature, and has its root, stem, leaves, 
and a bud, although these organs are often as undevel- 
oped in form as they are in size. 

As above mentioned, the chit of the seeds of maize and 
the other grains is the embryo. Its form is with diffi- 
culty distinguishable in the dry seeds, but when they 
have been soaked for several days in water, it is readily 
removed from the accompanying endosperm, and plainly 
exhibits its three parts, viz., i\\ii Radicle, the Plumule, 
and the Cotyledon, 

In Fig. 63 is represented the embryo of maize. In A 
and B it is seen in section imbedded in the endosperm. 
C exhibits the detached embryo. The Badicle, r, is the 
stem of the seed-plant, its lower extremity is the point 
from which downward growth proceeds, and from which 
the first true roots are produced. The Plumule, c, is 
the central bud, out of which the stem, with new leaves, 
flowers, etc., is developed. The Cotyledon, h, is in 
structure a ready-formed leaf, which clasps the i)lumule 
ill the embryo, as the 
jnoper leaves clasp the 
stem in the nuiture 
maize-plant. The coty- 
ledon of maize does not, 
however, perform the 
functions of a leaf ; on 
the contrary, it remains in the soil during the act of 
sprouting, and its contents, like tliose of the endosijerm, 
arc absorbed by the seedling. The first leaves which ap- 




REPIiODUCTIVE OliGANS OF PLxVisTS. 333 

jiear above-ground, in the case of maize and the other 
grains (buckwheat excepted), are tliose whicli in the 
embryo were wrapped together in the phimule, where 
they can be plainly distinguished by tlie aid of a mag- 
nifier. 

It will be noticed that the true grains (v/hich have 
sheathing leaves and hollow jointed stems) are monocot- 
yledonous (one-cotyledoned) in the seed. As has been 
mentioned, this is characteristic of plants with endoge- 
nous or inside-growing stems (p. 290). 

The seeds of t\\Q Exogens (outside-growers — p.29G) are 
dicotyledonous, i. e., have two cotyledons, Those of 
buckwheat, flax, and tobacco contain an endosperm. 
The seeds of nearly all other exogenous agricultural 
plants are destitute of an endosperm, and, exclusive of 
the coats, consist entirely of embryo. Such are the seeds 
of the Leguminos83, viz., the bean, pea, and clover; of 
the Cruciferge, viz., turnip, radish, and cabbage ; of ordi- 
nary fruits, the apple, pear, cherry, plum, and peach ; of 
the Gourd family, viz., the pumpkin, melon and cucum- 
ber ; and finally of many hard-wooded trees, viz., the 
oak, maple, elm, birch, and beecJi. 

We may best observe the structui-e of the two-cotyle- 
doned embryo in the ordinary garden- or kidney-bean. 
After a bean has been soaked in warm water for several 
hours, the coats may be easily removed, and the two 
lie shy cotyledons, c, v, in Pig. G4, are found separated 
from each otlier save at tlie point whore the radicle, a, is 
teen projecting like a bhint spur. On 
carefully breaking away one of the coty- 
ledons, we get a side view of tlie radicle, 
a, and plumule, h, the former of which 
was partially and the latter entirely im- 
bedded between the cotjdedons. The 
Fig. 64. plumule plainly exhibits tw^o delicate 

leaves, on which the unaided eye may note tlie veins. 




33-i HOW CROPS GROW. 

These leaves are folded together along their mid-ribs, and 
may be opened and spread out with help of a needle. 

When the kidney-bean (Phaseolns) germinates, the 
cotyledons are carried up into the air, where they become 
green and constitute the first pair of leaves of the new 
plant. The second pair are the tiny leaves of the plum- 
ule just described, between which is the bud, whence all 
the subsequent aerial organs develop in succession. 

In the horse-bean ( Vicia faba), as in the pea, the cot- 
yledons never assume the office of leaves, but remain in 
the soil and gradually yield a large share of their con- 
tents to the growing plant, shriveling and shrinking 
greatly in bulk, and finally falling away and passing into 
decay. 

§3. 

VITALITY OF SEEDS AlHD THEIR INFLUENCE ON THE 
PLANTS THEY PRODUCE. 

Duration of Vitality. — In the mature seed the em- 
bryo lies dormant. The duration of its vitality is very 
various. The seeds of the willow, it is asserted, will not 
grow after having once become dry, but must be sown 
when fresh ; they lose their germinative power in two 
weeks after ri])ening. 

On the other hand, single seeds of various plants, as of 
sorrel {Oi'alis striata), she[)herd'8 i)urse {T/ilnf^pi arv- 
eiise), anil esi)ecially of trees like the oaiv, beech, and 
cherry, remain with moist embryos many months or sev- 
eral years before sprouting. (Nobbe & Haenlcin, Vs. 
^/., XX, p. 79.) 

Among the seeds of various plants, clover for example, 
wliich, under favorable circumstances, mostly germinate 
within one or two weeks, may often be found a number 
which remain unchanged, sound and dry ivilldn, for 
months or years, though constantly wet externally. The 



RErRODUCTIYE OROAlirS OF PLAN"TS. 335 

outer coat of these seeds is exceptionally tliick, dense, 
and resistant to moisture. If this coat be broken by the 
scratch of a needle the seed will shortly germinate. In a 
collection of such seeds, kept in water, individuals sprout 
from time to time. In case of common sorrel (Eumex 
acefoseUa), N"obbe & Haenlein found that 10 per cent of 
the seeds germinated between the 400th and 500th day 
of keeping in the sprouting apparatus. 

The appearance of strange plants in earth newly 
thrown out of excavations may be due to the presence of 
such resistant seed, which, scratched by the friction of 
the soil in digging, are brought to germination after a 
long period of rest. Lyell states that seeds of the yellow 
Nelumbo (water lily) have sprouted after being in tlie 
ground for a century, and R. Brown is authentically 
said to have germinated seeds of a Nelumbo taken by 
him from Hans Sloane's herbarium, where they had been 
kept dry for at least 150 years. 

The seeds of wheat usually, for the most part, lose their 
power of growth after having been kept from three to 
seven years. Count Sternberg and others are said to 
have succeeded in germinating wheat taken from an 
Egyptian mummy, but only after soaking it in oil. 
Sternberg relates that this ancient wheat manifested no 
vitality when placed in the soil under ordinary circum- 
stances, nor even when submitted to the action of acids 
or other substances which gardeners sometimes employ 
with a view to promote sprouting. 

Girardin claims to have sprouted beans that were over 
a century old. It is said that Grimstone with great pains 
raised peas from a seed taken from a sealed vase found in 
the sarcophagus of an Egyptian mummy, presented to 
the British Museum by Sir Gr. Wilkinson, and estimated 
to be near 3,000 years old. 

Vilmorin, from his own trials, doubts altogether the 
authenticity of the '' mummy wheat," and it is probable 



336 HOW CRors grow, 

that those who hfivo raised mnmmy wheat or imimmy 
peas were deceived either by an admixture of fresh seed 
with the ancient, or by planting in ordinary soil, which 
commonly contains a variety of recent seeds that come 
to light under favorable conditions. 

Dietrich {Hoff. Jalir., 1862-3, p. 77) experimented 
with seeds of wheat, rye, and a species of Bromus, which 
were 185 years old. Nearly every means reputed to favor 
germination was employed, but without success. After 
proper exposure to moisture, the place of the germ was 
usually found to be occupied by a slimy, putrefying liq- 
uid. Commonly, among the freshest seeds, when put to 
the sprouting trial, some will mold or putrefy. 

The fact appears to be that the circumstances under 
which the seed is kept greatly influence the duration of 
its vitality. If seeds, when first gathered, be thoroughly 
dried, and then sealed up in air-tight vessels, there is no 
evident reason why their vitality should not endure for 
long periods. Moisture and the microbes that flourish 
where it is present, not to mention insects, are the agen- 
cies that usually put a speedy limit to the duration of 
the germ i native power of seeds. 

In agriculture it is a general rule that the newer the 
seed the better the results of its use. Experiments have 
proved that the older the seed the more numerous the 
failures to germinate, and the weaker the plants it pro- 
duces. 

Londet made trials in 1856-7 witli seed-wheat of the 
years 1856, '55, '54, and '53. The following table exhib- 
its the results : 

Number of stalks 

Per cent of seeds Leno'li of leaver four days and ears per 

sprouted. ' after coming up. hundred seeds. 

Seed of 1853 none 

" " 1854 51 0.4 to 0.8 inches. 269 

" " 18.55 73 1.2 " 365 

" " 1856 74 1.6 " 404 

The results of similar experiments made by Haberlandt 
on various grains are contained in the following table : 



REPRODUCTIVE ORGANS OF PLANTS. 337 

Per cent of seech that fjerminated in 18R1 from the years ; 

1850 185i 185A 1853 1857 1858 1859 1860 

Wheat 8 4 73 CO 84 96 

Rye 48 100 

Barley 24 48 33 92 89 

Oats .00 5(> 48 72 32 80 96 

Maize not tried 70 50 not tried 77 100 97 

Results of the Use of Long-kept Seeds. — The 
fact that old seeds yield weak plants is taken advantage 
of by the florist in producing new varieties. It is said 
that while the one-year-old seeds of Ten-weeks Stocks 
yield single flowers, those which have been kei^t four 
years give mostly double flowers. 

In case of melons, the experience of gardeners goes 
to show tliat seeds which have been kept several, even 
seven years, though less certain to come np, yield plants 
that give the greatest returns of fruit ; while plantings 
of new seeds run excessively to vines. 

Unripe Seeds. — Experiments by Lucanus i">rove that 
seeds gathered wdiile still unripe, — when the kernel is 
soft and milky, or, in case of cereals, even before starch 
has formed, and when the juice of the kernel is like 
water in appearance, — are nevertheless capable of germi- 
nation, especially if they be allowed to dry in connection 
with the stem (after-ripening). Such immature seeds, 
however, have less vigorous germinative power than 
those which are allowed to mature perfectly ; when sown, 
many of them fail to come up, and those which do, yield 
comparatively weak plants at first and in poor soil give a 
poorer harvest than well-ripened seed. In rich soil, 
however, the plants which do appear from unripe seed, 
may, in time, become as vigorous as any. (Lucanus, Vs. 
St., IV, p. 253.) 

According to Siegert, the sowing of unripe peas tends 
to produce earlier varieties. Liebig says: **The gar- 
dener is aware that the flat and shining seeds in the pod 
of the Stock Gillyflower will give tall plants with single 
flow^ers, while the shriveled seeds will furnish low plants 
with double flowers throughout. 23 



338 HOW CROPS GROW. 

Cohn found that seeds not fully ripe germinate some^ 
what sooner than those which are more mature, and he 
believes that seeds in a medium stage of ripeness germi- 
nate most readily. 

Quick- and Slow-Sprouting Seeds. — When a con- 
siderable number of agricultural or garden seeds, fresh 
and of uniform appearance, are placed under favorable 
circumstances for germinating, it is usually observed 
that sprouting begins within two to ten days, and con- 
tinues for one or several weeks before all or nearly all 
the living embryos have manifestly commenced to grow. 
Nobbe (in 1880 and 1887) found in extensive trials with 
12 varieties of stocks, Mattliiola annua, that the quick- 
sprouting seeds, which germinated in three to four days, 
yielded earlier and larger plants, which blossomed with 
greater regularity and certainty, and produced a pre- 
ponderance (82 per cent) of sterile double flowers, while 
the slow-sprouting seeds, that were ten to twelve days in 
germinating, gave smaller plants that came later to 
bloom, and yielded 73 per cent of fertile single flowers. 

Should continued trials prove these results to be of 
constant occurrence, it is evident that by breeding exclu- 
sively from the quick-sprouting seeds, the double -flower- 
ing varieties should soon become extinct, fiom failure to 
produce seed. On the other hand, exclusive use of the 
slow-sprouting seeds would extinguish the tendency to 
variation and double-blooming, v/hich gives this plant 
its vahie to the florist. 

Dwarfed or Light Seeds. — Miiller, as well as Hell- 
riegel, found in case of the cereals that light or small 
grain sprouts quicker but yields weaker plants, and is 
not so sure of germinating as heavy grain. 

Liebig asserts {Natural Laios of Husbandry, Am. 
Ed., 1863, p. 24) that '^poor and sickly seeds will pro- 
duce stunted plants, which will again yield seeds bearing 
in a great measure the same character." This is true 
*4n the long run," i. e., small or light seeds, the result 



REPRODUCTIVE ORGANS OF PLANTS. 339 

of unfavorable conditions, will, under the continuance 
of those conditions, produce stunted plants (varieties), 
whose seeds will be small and light. (Compare Tuscan 
and pedigree wheat, p. 158.) 

Schubart, whose observations on the roots of asfricul- 
tural plants are detailed in a former chapter (p. 2G3), 
says, as the result of much investigation, ^^the vigorous 
development of plants depends far less upon the size and 
weight of the seed than upon the depth to which it is 
covered with earth, and upon the stores of nourishment 
which it finds in its first period of life." Reference is 
here had to the immediate j^roduce under ordinary agri- 
cultural conditions. 

Value of Seed as Related to its Density. — From 
a series of experiments made at the Royal Agricultural 
College at Cirencester, in 1863-G, Church concludes that 
the value of seed-v/heat stands in a certain connection 
with its specific gravity {Practice loitli Science, pp. 107, 
342, 345, London, 1807). He found :— 

1. That seed-wheat of the greatest density produces 
the densest seed. 

2. The seed-wheat of the greatest density yields the 
greatest amount of dressed corn. 

3. The seed-wheat of medium density generally gives 
the largest number of ears, but the ears are poorer than 
those of the densest seed. 

4. The seed-wheat of medium density generally pro- 
duces the largest number of fruiting plants. 

5. The seed-wheats which sink in water, but float in a 
liquid having the specific gravity 1.247, are of very low 
value, yielding, on an average, but 34.4 lbs. of dressed 
grain for every 100 yielded by the densest seed. 

6. The densest wheat-seeds are the most translucent 
or horny, and contain about one-fourth more proteids 
(or 3 per cent more) than the opake or starchy grains 
from the same kind of wheat, or even from the same 
individual plant, or even from the same ear. 



340 HOW CROPS GROW. 

7. The weight of wheat per busliel depends upon 
many circnrastancos, and bears no constant relation to 
tlie density of the seed. 

The densest grains are not, according to Cluirch, 
always the largest. The seeds he experimented with 
ranged from sp. gr. 1.354 to 1.401. 

Marek has shown that specific gravity is no universal 
test of the quality of seed, for while, in case of wheat, 
flax, and colza, the large seeds are generally the denser, 
tl\e reverse is true of horse-beans ( Vicia faba) and peas 
(F.s^ St., XIX, 40). 

The Absolute Weight of Seeds from different 
varieties of tlie samo spoeios is known to vary greatly, 
as is well exemplified by comparing the kernels of com- 
mon field maize with those of ''pop corn." Similar dif- 
ferences are also observable in different single seeds from 
tlic same plant, or even from tho same pod or ear. Thns, 
Ilarz obtained what were, to all appearance, normally 
developed ceeds that varied in weight as follows : 

FROM SINGLE PLANTS. Milligrams. 

Wheat, Trlticmn vulr/are, from 15 to 37 

Wheat, Trlticum 2^olo>iicum, « 21 to 55 

liaiicy, Hordeum distichon, « 31 to 41 

Oats, Avoid sativa, •* 19 to 30 

Maize, Zca Mnys chiqtiantino, «< 1G9 to 201 

Pea, Pisum sativum, ' « 143 to 502 

FROM SINGLE FRUIT (PODS). 

Tea, . . .from 309 to 473 

Vtitch, u 33 lo G6 

Lvipin, .. 486 to 639 

Differences often no less marked nre found amons: the 
seeds in any considerable sample, gathered from a larsre 
number of plants and representing a crop. Nobbe, with 
great painstaking, has ascertained the average, maxi- 
mum and minimum weights, of 180 kinds of seeds, such 
as are found in commerce or are used in Agriculture, 
Horticulture, and Forestry. The following table gives 
some of his results : 



REPRODUCTIVE OROAT^TS OF ELAKTS. 3U 

Ahsohite Weight of Commercial Scoda. 

Number of AVcight of ono Seodin 
H;iiuples Milligvaius. 
Examined. Average. Maximum. Mininuim. 

Oats, 84 28.« 54.1 14.7 

iJarley 06 41.0 4«.'J 27.7 

Rye,...'. Ill) 23.3 47.i) 13.0 

AVlieat y5 37.6 45.8 15.2 

Maize,: 22 282.7 382.9 114.5 

Beet, 39 22.0 42.4 14.2 

Tvixnix), Brassica raplfcra,.. 23 2.2 3.0 1.4 

Carrot, 35 1.2 1.7 0.8 

Pea, 43 185.8 5G4.6 46.1 

Kidney Bean, /V<«6To/»s,.... 5 585.6 926.3 367.3 

Horse Eean, >'«ci«, 7 676.0 20C1.0 256.4 

Potato, 3 0.6 0.7 0.5 

Tomato, , 5 2.5 2.7 2.4 

«pinage, 4 6.9 9.0 2.4 

Radisn, 5 7.1 9.7 5.7 

Lettuce, 18 1.1 1.7 0.8 

Parsnip, 3 3.1 3.8 2.3 

Btpiash, 5 173.0 322.0 106.7 

Musk Aielon, 3 32.9 35.5 28.2 

Cueund.er, 6 25.4 27.0 21.0 

T\u\u\\\y, I'lilciiiii i>r<it('iii<e,. 73 0.41 0.59 0.34 

Rlue (4rass, /Vuf 7>/7f/^/^s/,s,.. 28 0.15 0.21 0.10 

Ked (lover, 355 1.60 2.0S 1.14 

Wliite (lover, 53 0.61 0.69 0.47 

Ten-weeks-si oeks, MaUld- 

ola. aiuiini, 4 1.50 1.60 1.39 

Oak, (Jiiei-ctis pedunculate,. 15 2013.4 4213.5 761.6 

It is noteworthy, that in case of Oats, Eye, AVheat, 
Maize, Beet, Spinage, and Sqnash, the heaviest seeds 
weigh tliricG as much as the lightest. With Turnip, 
Carrot, Kidney-bean, Lettuce, and Blue grass, some 
seeds are double the weight of others. The horse-bean 
gives some seeds eight times as heavy as others. Ilie 
differences brought out iii the Table in many cases are 
due to the representation of different varieties ; the 
larger seeds, to some extent, belonging to larger plants ; 
but the great range of weight, noted with regard to the 
seed of the Oal\, applies to 15 crops of sound acorns from 
one and the same tree, irathered in 15 successive years. 

In many varieties of Indian Corn, the kernels at the 
base of the enr are larger, and those at the tip are 
smaller, than those of the middle portion. Other varie- 
ties are characterized by great uniformity in the size of 
the kernels, having been '^ bred up " to this quality by 
careful seed-selection. 

It is well-known that the middle part of the ears of 



342 now CRors grow. 

wheat and barley produce the heaviest kernels. Nobbe 
nnmbcred and weighed the spikelets from an ear of six- 
rowed barley and from one of winter wheat. Either ear 
contained 27 spikelets, each with three kernels. The 
kernels of the smallest barley-spikelet, No. 2, from the 
base of the ear, weighed 1.5 milligrams; those of the 
largest, No. 10, weighed 103.5 mg. No. 27 weighed 
32.5 mg. The corresponding numbers in wheat weighed 
0.5, 34.5 and 10.8 mg. 

In case of barle}^, each of tiie first five spikelets, count- 
ing from the base, weighed less than 70 milligrams. 
The 6th to the 22d, inclusive, weighed 75 mg. or more. 
The 7th to the IGth weighed tJO mg. or more. The 17th 
to the 21st, 80 mg. or more. Thence, to the tip, the 
weight rapidly declined to nbout 30 milligrams. 

The wheat kernels exhibited quite similar variation of 
weight. 

Dividing the 27 spikelets into three groups of nine 
each, we have the following comparison of weights of 
seeds, to which is added the total lengths of the rootlets 
that were formed after germination had gone on for five 
days : 

BARLEY. WHEAT. 

Wei^-lit. Lengttli of Root. Weight. Length of Root. 
Spikelets, 1 to 420 mg. 670 mm. 153 mg. 223 mm. 

10 to 18 828 " 3281 " 282 " 1094 " 

18 to 27 512 •' 1364 " 191 " 454 «♦ 

The seeds of the middle portion of the ears of barley and 
wheat are thus seen to be very considerably heavier than 
those of either the base or tip, and also show greater ger- 
minative vigor, as measured by the comparative growth 
of the roots in a given short time. 

The greater weight and germinative energy of the 
seeds from the middle of the ears, stand in relation to 
the fact that these seeds are the oldest— the flowers from 
which they deyelop being the first to open and fructify. 
In case of a head of summer rye, Nobbe found that the 



KEPRODUCTIVE ORGANS OF PLANTS. 343 

33 spikelets, each with two buds, required a iveeh for 
blossoming ; the first of the 66 flowers to open were 
mostly those of tlie thirties and forties, and the last 
those of the tens, fifties, and sixties, counting from the 
base upward. These middle seeds had accordingly an 
earlier start, aud better chance for full development, 
than those at the base and i\\) of the ear. 

Oat kernels usually grow in pairs, the upper one of 
each pair being in general lighter and smaller than the 
lower one. Nobbe counted out 200 upper kernels, 200 
lower kernels, and 200 average kernels, without selection. 
These were weighed, and, after soaking in water for 24 
hours, were placed in a sprouting apparatus at a tem- 
perature of about 70° F. The results were as follows : 

100 seeds Number of seeds that sprouted. 

weighed. On the Total in 

Grams. 3d, 4th, 5th, Oth, 7th, 8th, 9th, 10th days. 10 days. 
Upper Kernels, 1..53 2 100 76 15 3 2 1 199 

Lower Kernels, 3.46 109 75 9 3 2 198 

Average Kernels, 2.09 45 110 30 8 4 11 199 

Here, as in case of wheat and barley, the light seeds 
were slower to germinate. 

In general, it would appear that, other things being 
equal, stronger and more perfect plants and larger 
crops are produced from heavy than from small seeds. 
Many comparisons are on record that have given such 
results ; not only small trials in garden plats, but also 
field experiments on a larger scale. 

Lehmann sowed, on each of three jdats of 92 square 
feet, the same numl)er (528) of peas, of the same kind 
but of different weight, with results as here tabulated • 

Weights of 100 No. of Yield (grams). 

seed-peas, plants. Kernels. Pods. Straw. Total. 

Small seed-peas, 160 gm. 423 998 280 2010 3288 

Medium seed-peas, 221 " 478 1495 357 2630 4482 

Large seed-peas, 273 " 480 1814 437 3170 5421 

Of the peas sown, there failed to germinate about 9 



ods. 


Straw. 


Total, 


66 


475 


777 


75 


550 


9;j8 



344 HOW CROPS GROW. 

per cent, botb of the large and medium sizes, and 20 per 
cent ot' the small ones. 

The total produce from the small seeds was less abun- 
dant in all respects than that of the medium, and this 
less than that of the large seeds. 

Calculated upon the same number of plants, the differ- 
ences, though less in degree, are still very decided : 

100 Plants Yielded Kernels. 

From small seeds, 236 

From medium seeds, 313 

From large seeds, 378 91 660 1129 

Lehmanu, in another experiment, found that from the 
same weight of seed a larger crop is given by large seed 
than by small, although the number of plants may be 
considerably less. 

From the same weight (188 gm.) of seed-peas were 
produced : 

Number of Weight of Kernels 

Feed-peas, i'lants. per 92 sq. ft. Per 100 plants. 
By small seed, 780 680 1590 234 

By medium seed, 530 505 2224 440 

By large seed, 384 360 2307 640 

Driesdorff sowed separately, on the same land, winter 
wheat, as winnowed, and the same divided by sifting into 
three sizes. In April and May the vegetation from the 
largest seed was evidently in advance, and at harvest 
the relative yield for 100 of unsifted seed was 121 from 
the largest, 105 for the medium, and 95 for the smallest 
seed. 

Improved varieties are often the result of continued 
breeding from the heaviest or largest seeds, accompanied 
by high culture on rich soil, and thin planting, so that 
the roots have abundant earth for unhindered develoj^- 
ment. 

Ilallet, in 1857, selected two ears of Nursery Wheat, 
'' the finest rpiality of red wheat grown in England," con- 
taining, together, 87 grains, and planted the kernels 12 
inches apart every way. At harvest one prime grain 



REPRODUCTIVE ORGANS OF PLANTS. 34ji 

prodncecl 10 ears, tliafc contained in the aggregate 688 
kernels. Tlie finest 10 ears that could be selected from 
the whole produce of the other 86 grains yielded but 
598 kernels. The 79 kernels of the one best ear were 
planted as before, and the produce of the finest seed, a.^ 
shoivn hy the harvest, was used for the next year's sow- 
ing. The results of continuing this process of selection 
are tiibulated below : 

Number of 
Length, Containing, ears on 

Y^^^' inches. grains. finest stool. 

1857. Original, 4a 47 

1858. Finest ear, GJ 79 10 

1859. Finest ear, 7| 91 22 

18G0. Ears imperfect from ivet season, ... 39 

18G1. Finest ear, 8| 123 52 

In five years, accordingly, the length of the cars was 
doubled, their contents nearly trebled, and the tillering 
capacity of the plant increased five-fold. {Journal Royal 
Ag. 80c. , XXII, p. 374.) 

Wollny has given account of 27 garden trials, with 
large and small seeds of rye, buckwheat, beans, vetclies, 
peas, lupins, soybeans, colza, mustard, maize, and rcd- 
clovcr, on ])lats of four square meters (43 sq. ft.), during 
the years 1873 to 1880, with the nearly invariable results : 
1, that the quantity of crop increases with the size of 
the seed ; 3, that the large seed produces jirincipally 
large seed, and the small seed small ; 3, that the relative 
productiveness of the small seed is greater than that of 
the large ; and 4, that the vitality of the i)]ants from 
small seed is usually less than that of the jdants from 
large seed. 

The facts of experience fully justify the conclusion 
that, in general, other things being equal, the heaviest 
seed is the best. 

Signs of Excellence. — So far as the common judg- 
ment can determine by external signs, the best seedis that 
which, on the one hand, is large, plump, and heavy, and on 



346 now CROPS grow. 

the other is fresh or bright to the eye, and free from 
musty odor. The kirge, plum]^, and heavy seeds are 
those which have attained the fullest development, and 
can best support the embryo when it shall begin to 
grow ; those fresh in color and odor are likely to be new, 
and to have the most vigorous vitality. 

Ancestry ; Race-Vigor ; Constancy. — There are, 
however, important cpialities in seed that are involved in 
their heredity and give no outward token of their pres- 
ence. Eace-vigor and Constancy are qualities of this 
sort, and these wonderfully persist in some kinds of seed 
and are kicking in others. All cultivated plants occur 
in numerous varieties, and, as the years go on, older 
varieties "run out " or are neglected and forgotten, their 
place being taken by newer and often, or for a time, bet- 
ter ones. It would appear that a long course of careful 
cultivation under the most favorable and uniform condi- 
tions, coupled with careful and intelligent selection of 
seed from the best-developed plants, not only leads to 
tlie formation of the best varieties, but tends to establish 
their permanence, so that when soil, climate, and care 
are unfavorable, the kind maintains its character and 
makes a stout resistance to deteriorating influences. 

In order to properly appreciate the value of seed, its 
Pedigree must therefore be known. But seed of ances- 
try, that has a long-established character for certain 
(pialities, in a given locality, may prove of little value 
under widely different circumstances, or, if its products 
be cultivated under new conditions, it may lose its char- 
acteristics more or less, and develo[) into other varieties. 
It is well known that various perennial plants of tropical 
climates, like the castor bean, become annuals in north- 
ern latitudes, and it may easily happen that the seed of 
some prized variety wliicli is of unquestioned pedigree, as 
far as the remote lines of its descent can indicate, is of lit- 
tle worth in soils or climates to which it is unaccustomed, 



REPRODUCTIVE ORGANS OF PLAJ^TS. 347 

from not having the power to transmit the specially 
valuable qualities of its progenitors. In high, northern 
latitudes, the summer cereals ripen after a short period 
of rapid growth, but seed of such grain, sown in the soil 
of temperate regions, does not produce early varieties ; its 
rate of growth, after a few years at most, is governed by 
the climate to which it is exposed. In considering the 
pedigree of seed, therefore, it is not merely the repute 
or characters of the ancestry, but the probability that 
the ancestral excellencies reside in and will be trans- 
mitted by the seed, that constitutes the practical point. 



DIVISION III. 

LIFE OF THE PLANT. 

CIIAPTEIl I. 

GERMINATION. 

§ 1- 
INTRODUCTORY. 

Having traced the composition of vegetation from its 
ultimate elements to the proximate organic compounds, 
and studied its structure in the simple cell as well as in 
the most highly-developed plant, and, as far as needful, 
explained the characters and functions of its various 
organs, we approach the subject of Vegetable Life 
and Nutrition, and are ready to inquire how the plant 
increases in bulk and weight and produces starch, sugar, 
oil, albuminoids, etc., which constitute directly or in- 
directly almost the entire food of animals. 

The beginning of the agricultural plant is in the 
flower, at the moment of fertilization by the action of a 
pollen tube on the contents of the embryo-sack. Each 
embryo whose development is thus ensured is a plant in 
miniature, or ratlier an organism that is capable, under 
proper circumstances, of unfolding into a plant. 

349 



350 HOW CROPS GKOW. 

The first process of development, wherein the young 
plant commences to manifest its separate life, and in 
which it is shaped into its proper and peculiar form, is 
called germination. 

The CrE^EFtAL PROCESS and Conditions of Germin- 
ation are familiar to all. In agriculture and ordinary 
gardening we bury the ripe and sound seed a little way 
in the soil, and in a few days, or weeks, it usually sprouts, 
provided it finds a certain degree of warmth and moisture. 

Let us attend somewhat in detail first to the phenom- 
ena of germination and afterward to the requirements of 
the awakening seed. 



2. 



THE PHENOMENA OF GERMINATION. 

The student will do well to watch with care the various 
stages of the act of germination, as exhibited in several 
species of plants. For this purpose a dozen or more 
seeds of each plant are sown, the smaller, one-half, the 
larger, one inch deep, in a box of earth or sawdust, kept 
duly warm and moist, and one or two of each kind are 
uncovered and dissected jit successive intervals of 12 
hours until tlie process is complete. In this way it is 
easy to trace all the visible changes which occur as tlie 
embryo is quickened. The seeds of the kidney-bean, 
pea, of maize, buckwheat, mid barley, may be employed. 

We thus observe that the seed first absorbs a large 
amount of moisture, in consequence of which it swells 
and becomes more soft. We see the germ enlarging be- 
neath the seed coats, shortly the integuments burst and 
the radicle appears, afterward the plumule becomes 
manifest. 

In all agricultural plants the radicle buries itself in 



GERMINATION^. 351 

the soil. The plumule ascends into the atmosphere and 
seeks exposure to the direct light of the sun. 

The endosperm, if the seed have one, and in many- 
cases the cotyledons (so with the horse-bean, pea, maize, 
and barley), remain in the place where the seed was 
deposited. In other cases (kidney-bean, buckwheat, 
squash, radisb, etc.) the cotyledons ascend and become 
the first pair of leaves. 

The ascending plumule shortly unfolds new leaves, 
and, if coming from the seed of a branched plant, lateral 
buds make theii' appearance. The radicle divides and 
subdivides in beginning the issue of true roots. 

When the phmtlet ceases to derive nourishment from 
the mother-seed the process is finished. 

§ 3. 

THE CONDITIONS OF GERMINATION. 

As to the Conditions of Germination we have to con- 
sider in detail the following : — 

a. Temperature.— Seeds sprout within certain more 
or less narrow limits of warmth. 

Sachs has approximately ascertained, for various agri- 
cultural seeds, the limits of warmth at which germina- 
tion is possible. The lowest temperatures range from 
below 40° to 55", the highest, from 102° to 110°. Below 
the minimum temperature a seed preserves its vitality, 
above the maximum it is killed. He finds, likewise, that 
the point at which the most rapid germination occurs is 
intermediate between these two extremes, and lies be- 
tween 79° and 93°. Either elevation or reduction of 
temperature from these degrees retards the act of 
sprouting. 

In the following table are given the special tempera- 
tures for six common plants : 



352 HOW CROPS GROW. 





Lowest 


Highest 


Temperature of most 




TemiJerature. 


Temperature. 


rapid 


Germination. 


Wheat,* 


40^ F. 


104^ F. 




84° F. 


Barley, 


41 


104 




84 


Fea, 


44.5 


102 




84 


Maize, 


48 


115 




93 


Scarlet-bean, 


49 


111 




79 


Squash, 


54 


115 




93 



For the agricultural plants cultivated in New England, 
a range of temperature of from 55° to 90° is adapted for 
healthy and speedy germination. 

It will be noticed in the above Table that the seeds of 
plants introduced into northern latitudes from tropical 
regions, as the squash, bean, and maize, require and 
endure higher temperatures than those native to temper- 
ate latitudes, like wheat and barley. The extremes given 
above are by no means so wide as would be found were 
we to experiment with other plants. Some seeds will 
germinate near 32°, the freezing point of water, as is 
true of wiieat, rye, and water-cress, as well as of various 
alpine plants that grow in soil wet with the constant 
drip from melting ice. On the other hand, the cocoa- 
nut is said to yield seedlings with greatest certainty when 
the heat of the soil is 120°. 

Sachs has observed that the temperature at which 
germination takes place materially influences the relative 
development of the parts, and thus the form, of the seed- 
ling. Very low temperatures retard the production of 
new rootlets, buds, and leaves. The rootlets which are 
rudimentary in the embryo become, however, very long. 
On the other hand, very high temperatures cause the 
rapid formation of new roots and leaves, even before 
those existing in the germ are fully unfolded. The 
medium and most favorable temperatures bring the 
parts of the embryo first into development, at the same 
time the rudiments of new organs are formed which are 
afterwards to unfold. 



* Wheat, and probably barley, may, occasionally, germinate at, or 
very near, 32'^. 



GERMINATION". 353 

b. Moisture. — A certain amount of 7noisture is indis- 
pensable to all growth. In germination it is needful 
that the seed should absorb water so that motion of the 
contents of the germ-cells can take place. Until the 
seed is more or less imbued with moisture, no signs of 
sprouting are manifested, and if a half-sprouted seed 
be allowed to dry the process of growth is effectually 
checked. 

The degree of moisture different seeds will endure or 
require is exceedingly yarious. The seeds of aquatic 
plants naturally germinate when immersed in water. 
The seeds of most agricultural plants, indeed, will 
quicken under water, but they germinate most health- 
fully when moist but not wet. Excess of water often 
causes seeds to rot. 

c. Oxygen Gas. — Free Oxygen, as contained in the 
air, is likewise essential. Saussure demonstrated by ex- 
periment that projier germination is impossible in its 
absence, and cannot proceed in an atmosphere of other 
gases. The chemical activity of oxygen appears to be 
the means of exciting the gi'owth of the embryo. 

d. Light. — It has been erroneously taught that liglit 
is prejudicial to germination, and that therefore seed 
must be covered. {Johnston'' s Lectures on Ag. Cliem, S 
Geology, 2d Eng. Ed., pp 226 and 227.) Nature does 
not bury seeds, but scatters them on the surface of the 
ground of forest and prairie, where tliey are, at the most, 
half-covered and by no means removed from the light. 
The warm and moist forests of tropical regions, which, 
though shaded, are by no means dark, are covered with 
sprouting seeds. The seeds of heaths, calceolarias, and 
some other ornamental plants, germinate best when un- 
covered, and the seeds of common agricultural i:)lants 
will sprout when placed on moist sand or sawdust, with 
apparently no less certainty than when buried out of 
sight. 

23 



354 now CROPS grow. 

Finally, R. Iloffmanri (Jahresbericht fiber AgricnUur 
Chem., 1864, p. 110) found, in special experiments with 
24 kinds of agricultural seeds, that light exercises no 
appreciable influence of any kind on germination. 

The time required for Germination varies exceed- 
ingly according to the kind of seed. It is said that the 
fresh seeds of the willow begin to sprout within 12 hours 
after falling to the ground. Those of clover, wheat, and 
other grains, mostly germinate in three to ten days. 
The fruits of the walnut, pine, and larch lie four to six 
weeks before sprouting, while those of some species of 
ash, beech, and maple are said not to germinate before 
the expiration of one and a half or two years. 

The starchy and thin-skinned seeds quicken most 
readily. The oily seeds are in general more slow, while 
such as are situated within thick and horny or other- 
wise resistant envelopes require the longest periods to 
excite growtli. 

The time necessary for germination depends naturally 
upon the favorableness of other conditions. Cold and 
drought delay the process, when they do not check it 
altogether. Seeds that are buried deeply in the soil may 
remain for years, preserving, but not manifesting, their 
vitality, because they are either too dry, too cold, or 
have not sufficient access to oxygen to set the germ in 
action. 

Notice has already been made of the frequent presence 
in clover -seed, for example, of a small proportion of 
seeds that have a dense coat which prevents imbibition 
of water and delays their germination for long periods. 
See p. 335. 

To speak with precision, we should distinguish the 
time from planting the dry seed to the commencement 
of germination, which is marked by the rootlet becom- 
ing visible, and the period that elapses until the process 
is complete ; i. e., until the stores of the mother-seed are 



GERMIKATIOK. 355 

exhausted, and the young plant is wholly cast npon its 
own resources. 

At 41° F., in the experiments of Haberlandt, the root- 
let issued after four days, in the case of rye, and in five 
to seven days in that of the other grains and clover. 
The sugar-beet, however, lay at this temperature 22 days 
before beginning to sprout. 

At 51°, the time was shortened about one-half in case 
of the seeds just mentioned. Maize required 11, kidney- 
beans 8, and tobacco 31 days at this temperature. 

At 65° the cereals, clover, peas, and flax began to 
sprout in one to two days ; maize, beans, and sugar-beet 
in three days, and tobacco in six days. 

The time of completion varies with the temperature 
much more than that of beginning. It is, for example, 
according to Sachs, 

at 41—55° for wheat and barley 40 — 15 clays. 
at<J5— 100^ " " 10—12 " 

At a given temperature small seeds complete germina- 
tion much sooner than large ones. Thus at 55-60° the 
process is finished 

with beans in 30 — 40 days. 
" maize in 30—35 " 
" wheat in 20—25 •• 
" clover in 8—10 " 

These differences are simply due to the fact that the 
smaller seeds have smaller stores of nutriment for the 
young plant, and are therefore more quickly exhausted. 

Proper Depth of Sowing. — The soil is usually the 
medium of moisture, warmth, etc., to the seed, and it 
affects germination only as it influences the supply of 
these agencies ; it is not otherwise essential to the pro- 
cess. The burying of seeds, when sown in the field or 
garden, serves to cover them away from birds and keep 
them from drying up. In the forest, at spring-time, we 
may see innumerable seeds sprouting upon the surface, 
or but half covered with decayed leaves. 



356 now CROPS grow. 

While it is the nearly universal result of experience in 
temperate regions that agricultural seeds germinate most 
surely when sown at a depth not exceeding one or two 
inches, there are circumstances under which a widely 
different practice is admissible or even essential. In the 
light and porous soil of the gardens of New Haven, peas 
may be sown six to eight inclies deep without detriment, 
and are thereby better secured from the ravages of the 
domestic pigeon. 

The Moc[ui Indians, dwelling upon the table lands of 
the liigher Colorado, deposit the seeds of maize 12 or 14 
inches below the surface. Thus sown, the plant thrives, 
while, if treated according to the plan usual in the 
United States and Europe, it might never appear above 
ground. The I'casons for such a procedure are the fol- 
lov/ing : The country is without rain and almost with- 
out dew. In summer the sandy soil is continuously 
parched l)y the sun, at a temperature often exceeding 
100° in the shade. It is only at the depth of a foot or 
more that the seed finds the moisture needful for its 
growth — moisture furnished by the melting of the winter 
snows.* 

R. Hoffmann, experimenting in a light, loamy sand, 
upon 24 kinds of agricultural and market-garden seeds, 
found that all perished when buried 12 inches. When 
planted 10 inches deep, peas, vetches, beans, and maize, 
alone came up ; at 8 inches there appeared, besides the 
above, wheat, millet, oats, barley, and colza ; at 6 inches, 
those already mentioned, together with winter colza, 
buckwheat, and sugar-beets ; at 4 inches of depth the 
above and mustard, red and white clover, flax, horse- 
radish, hemp, and turnips ; finally, at 3 inches, lucern 
also appeared. Hoffmann states that the deep-planted 
seeds generally sprouted most quickly, and all early dif- 

* For these interesting facts, the writer is indebted to Prof. J. S. 
Newberry. 



GERMINATION^'. 357 

fereiicGS in development disappeared before the plants 
blossomed. 

On the other hand, Grouven, in trials with sugar-beet 
seed — made, most probably, in a well-manured and rather 
heavy soil — found that sowing at a depth of three-eighths 
to one and a fourth inches gave the earliest and strongest 
plants ; seeds deposited at a depth of two and a half 
inches required five days longer to come up than those 
planted at three-eighths of an inch. It was further shown 
that seeds sown shallow, in a fine wet clay, required four 
to five days longer to come up than those placed at the 
same depth in the ordinary soil. 

Not only the character of the soil, which influences the 
supply of air and warmth, but the kind of weather 
which determines both temperature and degree of moist- 
ure, have their effect upon the time of germination, and 
since these conditions are so variable, the rules of prac- 
tice are laid down, and must be received, with a certain 
latitude. 

§ 4. 

THE CHEMICAL PHYSIOLOGY OF GERMINATION. 

The Nutrition of the Seedling. — The young 
plant grows at first exclusively at the expense of the 
seed. It may be aptly compared to the suckling animal, 
which, when new-born, is incapable of j^i'oviding its 
own nourishment, but depends upon the milk of its 
mother. 

The Nutrition of the Seedling falls into three pro- 
cesses, which, though distinct in character, proceed sim- 
ultaneously. These are : 1, Solutio7i of the Nutritive 
Matters of the Cotyledons or Endosperm ; 2, Transfer; 
and 3, Assimilation of the same. 

1. The Act of Solution has no difficulty in case of 



358 now CROPS GROW. 

dextrin, gum, the sugars, and soluble prot.eids. The 
water which the seed imbibes, to the extent of one-fourth 
to five-fourths of its weight, at once dissolves them. 

It is otherwise with the fats or oils, with starch and 
with proteids, which, as such, are nearly or altogether 
insoluble in water. In the act of germination provision 
is made for transforming these bodies into tlie soluble 
ones above mentioned. So far as these changes have 
been traced, they are as follows : 

Solution of Fats. — Sachs was the first to show that 
squash-seeds, which, when ripe, contain no starch, 
sugar, or dextrin, but are very rich in oil (50%) and 
albuminoids (4C%), suffer by germination such chemical 
change that the oil rapidly diminishes in quantity (nine- 
tcnths disappear), while, at the same time, starcli, and 
in some cases sugar, is formed. (Vs. St., Ill, p. 1.) 

Solution of Starch. — The starch that is thus organized 
from the fat of the oily seeds, or that which exists 
ready-formed in the farinaceous (floury) seeds, undergoes 
further changes, which have been previously alluded to 
(p. 50), whereby it is converted into substances tlmt are 
soluble in water, viz., dextrin and dextrose. 

Solution of Alhuminoids. — Finally, the insoluble al- 
buminoids are gradually transformed into soluble modi- 
fications. 

Chemistry of Malt. — The preparation and proper- 
ties of 7nalt may serve to give an insight into the nature 
of the chemical metamorphoses that have just been 
indicated. 

Tlie preparation is in this wise. Barley or wheat 
(sometimes rye) is soaked in water until the kernels are 
soft to the fingers ; then it is drained and thrown up in 
heaps. The masses of soaked grain shortly dry, become 
heated, and in a few days the embryos send forth their 
radicles. The heaps are shoveled over, and spread out 
so as to avoid too great a rise of temperature, and when 



GERMINATION". 350 

the sprouts arc about half an inch in length, the germin- 
ation is checked by drying. The dry mass, after remov- 
ing the sprouts (radicles), is malt, such as is usei in the 
manufacture of beer. 

Malt thus consists of starchy seeds, whose germination 
has been checked while in its early stages. The only 
product of the beginning growth — the sprouts — being 
removed, it exhibits in the residual seed the first results 
of the process of solution. 

The following figures, derived from the researches of 
Stein, in Dresden ( V/ilda's Gentralblatt, 1830, 2, pp. 8- 
23), exhibit the composition of 100 parts of Barley, and 
of the 92 parts of Malt, and the two and a half of Sprouts 
which 100 parts of Barley yield.* 

romtwsition of ^"^ 1^^^- «f I - I »2 pts. of ) , ( 2^ of ) , 

^composition or Barley. (-{ Malt. ( + 1 Sprouts. J + 

Ash, 2.42 

Starch, 54.48 

Fat, 3.56 

Insoluble Albuminoids, 11.02 

Soluble Albuminoids, 1.2G 

Dextrin, t G.50 

Extractive Matters (soluble in 
water and destitute of nitrogen) 0.90 
Cellulose, 19.8G 



I pts. o 
Malt. 


'1 + 


1 


2^ of 
Sprouts, 


2.11 






0.29 


47.43 








2.0') 






0.08 


9.02 






0.37 


1.9G 






0.40 


G.95^i 






0.47 


3.G8 








18.7G 






0.89 



100. 92. 2.5 

It is seen from the above statement that starch, fat, 
and insoluble albuminoids have diminished in the malt- 
ing process ; while soluble albuminoids, dextrin, and 
other soluble non-nitrogenous matters have somewhat 
increased in quantity. With exception of 3% of soluble 
"^extractive matters," J the differences in composition 
between barley and malt are not striking. 



* The analyses refer to the materials in the dry state. Ordinarily 
they contain from 10 to ir> ])er cent of water. It must not be omitted to 
mention that the iir()pf)rtions of malt and sprouts, as well as tlieir 
composition, vary soin<>what according to circumstances ; and further- 
more, the best analyses which it is possible to make are but approxi- 
mate. 

t Later investigators deny the existence of dextrin in barley, but 
find, instead, amidulin and amylan. See p. G2, note. 

J The term extraetlva viatters ishere applied to soluble substances, 
whose precise nature is ]K)t underslt)od. Tlicy constitute a. mixture 
which the chemist is not able to analyze. 



3G0 now CHOPS grow. 

The properties of the two are, however, remarkably 
different. If malt be pulverized and stirred in warm 
water (155° F.) for an hour or two, the whole of the 
starch disappears, while sugar and dextrin take its place. 
The former is recognized by the sweet taste of the wort, 
as the solution is called. On heating the wort to boiling, 
a little albuminoid is coagulated, and may be separ- 
ated by filtering. This comes in part from the trans- 
formation of tlie insoluble albuminoids of the barley. 
On adding to the filtered liquid its own bulk of alcohol, 
dextrin becomes evident, being precipitated as a white 
powder. 

Furthermore, if we mix two to three parts of starch 
with one of malt, we find that the whole undergoes the 
same change. An additional quantity of starch remains 
unaltered. 

The process of germination thus develops in the seed 
an agency by Avhich the conversion of starch into soluble 
carbhydrates is accomplished with great rapidity. 

Diastase. — Payon & Persoz attributed this action to 
the nitrogenous ferment which they termed Diadase, 
and which is found in the germinating seed in the vicin- 
ity of the embryo, but not in the radicles. They assert 
that one part of diastase is capable of transforming 2,000 
parts of starch, first into dextrin and finally into sugar, 
and that malt yields one five-hundredth of its weight of 
this substance. See p. 103. 

A short time previous to the investigations of Payen 
& Persoz (1833), Saussure found that Mucedin,* the 
soluble nitrogenous body which may be extracted from 
gluten (p. 92, note), transforms starch in the manner 
above described, and it is now known that various albu- 
minoids may produce the same effect, although the rap- 



* 8;iussiirc designated this Ixxly mxcin, but this term being established 
as t]ie name of tlie eliaraeteristie ingredient of animal mueus, Kittliau- 
seji has rex>laeed it by mueedin. 



GERMINATION". 



361 



idity of the action and the amount of effect arc usually 
far less than that exhibited by the so-called diastase. 

It must not be forgotten, however, that in all cases in 
wliicli the conversion of starch into dextrin and. sng-ar is 
accomplished artificially, an elevated temperature is re- 
quired, whereas, in the natural process, as shown in the 
germinating seed, the change goes on at ordinary or even 
low temperatures. 

It is generally taught that oxygen, acting on the albu- 
minoids in presence of water, and within a certain range 
of temperature, induces the decomposition which confers 
on them the power in question. 

The necessity for oxygen in the act of germination has 
been thus accounted for, as needful to the solution of 
the starch, etc, , of the cotyledons. 

This may be true at first, but, as we shall presently see, 
the chief action of oxygen is probably of another kind. 

How diastase or other similar substances accomplish 
the change in question is not certainly known. 

Soluble Starch. — The conversion of starch into 
Bugar and dextrin is thus in a sense explained. This is 

3^- ;^\ not, however, the only cliange 

2/ of which starch is suscepti- 
ble. In the bean (Pltascol- 
us multiflorus) Sachs [Sitz- 
u ngsiericlt te d e r Wi ener 
Akad., XXXVII, 57) in- 
forms us that the starch of 
the cotyledons is dissolved, 
passes into the seedling, and 
reappears (in part, at least) 
as starch, without conver- 
sion into dextrin or sugar, 
as these substances do not appear in the cotyledons during 
any period of germination, except in small quantity near 
the joining of the seedling. Compare \). b2, Amidulin. 




363 now CROPS grow. 

The same authority gives the following acconnt of the 
microscopic changes observed in the starch-grains them- 
selves, as they undergo solution. The starch-grains of 
the bean have a narrow interior cavity (as seen in Fig. 
60, 1). This at first becomes filled with a liquid. 
Next, the cavity appears enlarged (2), its borders assume 
a corroded appearance (3, 4), and frequently channels 
are seen extending to the surface (4, 5, 6). Finally, the 
cavity becomes so large, and the channels so extended, 
that the starch-giain falls to pieces (7, 8). Solution 
continues on the fragments until they have completely 
disappeared. 

Soluble Albuminoids. — The insoluble proteids of 
the seed are gradually transferred to the young plant, 
probably by ferment-actions similar to those referred 
to under the heading '* Proteoses and Peptones," p. 100. 

The production of small quantities of acetic and lactic 
acids (the acids of vinegar and of sour milk) has been 
observed in germination. These acids perhaps assist in 
the solution of the albuminoids. 

Gaseous Products of Germination. — Before leav- 
ing this part of our subject, it is proper to notice some 
other results of germination which have been thought to 
belong to the process of solution. On referring to the 
table of the composition of malt, we find that 100 parts 
of dry barley yield 92 parts of malt and 2^ of sprouts, 
leaving 5|- parts unaccounted for. In the malting pro- 
cess, 1^ parts of the grain are dissolved in the water in 
wliich it is soaked. The remaining 4 parts escape into 
the atmosphere in the gaseous form. 

Of the elements that assume the gnseous condition, 
carbon does so to the greatest extent. It unites with 
atmospheric oxygen (partly with the oxygen of the 
seed, according to Oudemans), producing carbonic acid 
gas (COo). Hydrogen is likewise separated, partly in 
union with oxygon, as water (II2O), but to some degree 



GERMINATION. 3G3 

ill the free state. Free nitrogen api)ears in considerable 
amount (Scliulz, Jour, far Frakt. Chem., 87, p. 103), 
while very minute quantities of Hydrogen and of Nitro- 
gen combine to gasaous ammonia (NH3). 

Heat developed in Germination. — These chemical 
changes, like all processes of oxidation, are accompanied 
with the production of heat. The elevation of temper- 
ature may be imperceptible in the germination of a sin- 
gle seed, but the heaps of sprouting grain seen in the 
malt-house, warm so rapidly and to such an extent that 
much care is requisite to regulate the process ; otherwise 
the malt is damaged by over-heating. 

2. The Transfer of the Nutriment of the Seed- 
ling from the cotyledons or endosperm where it has un- 
dergone solution, takes place through the medium of the 
water which the seed absorbs so largely at first. This 
water fills the cells of the seed, and, dissolving their con- 
tents, carries them into the young plant as rapidly as 
they are required. The path of their transfer lies through 
the point where the embryo is attached to the cotyle- 
dons ; thence they are di;:^tributed at first chielly down- 
wards into the extending radicles, after a little Avhile 
both downwards and upwards toward the extremities of 
the seedling. 

Sachs has observed that the carbhydratcs (sugar and 
dextrin) occupy the cellular tissue of the rind and pith, 
which are i)enetrated by numerous air-i)assages ; while 
at first the albuminoids chielly difi'use themselves through 
the intermediate cambial tissue, which is destitute of 
uir-passages, and are present in largest relative quantity 
at the extreme ends of the rootlets and of the plumule. 

In another chapter we shall notice at length the phe- 
nomena and physical laws which govern the diffusion of 
liquids into each otlier and through membranes similar 
to those which constitute the walls of the cells of plants, 
and there shall be able to e^^ither some idea of the causes 



3Gi HOW CHOPS GROW. 

which set up and maintain the transfer of the materials 
of the seed into the infant phmt. 

3. Assimilation is the conversion of the transferred 
nutriment into the substance of the pUmt itself. This 
process involves two stages, the first being a chemical, 
the second, a structural transformation. 

Tlie chemical changes in the embr}'o are, in part, 
simply the reverse of those which occur in the cotyle- 
dons ; viz., the soluble and structureless proximate prin- 
ciples are metamorphosed into the insoluble and oj'gan- 
ized ones of the same or similar chemical composition. 
Thus, dextrin may pass into cellulose, and the soluble 
albuminoids may revert in part to the insoluble condi- 
tion in which they existed in the ripe seed. 

But many other and more intricate changes proceed in 
the act of assimilation. With regard to a few of these 
we have some imperfect knowledge. 

Dr. Sachs informs us that when the embryo begins to 
grow, its expansion at first consists in the enlftrgement 
of the r,eady-formed cells. As a part elongates, the 
starch which it contains (or which is formed in tlie early 
stages of this extension) disajjpears, and sugar is found 
in its stead, dissolved in the juices of the cells. When 
the organ has attained its full size, sugar can no longer 
be detected ; Avhile the walls of the cells are found to 
have grown both in circumference aiul thickness, thus 
indicating tiie acciunuhition of cellulose. 

Oxygen Gas needful to Assimilation. — Traube 
has made some experiments, which jirove conclusively 
that the process of assimilation requires free oxygen to 
surround and to be absorbed by the growing parts of the 
germ. This observer found that newly-s])routed pea- 
seedlings continued to develop in a normal manner when 
the cotyledons, radicles, and lower part of the stem 
were withdrawn from the influence of oxygen by coat- 
ing with varnish or oil. On the other hand, when the 



GERMIl^ATION-. 3G5 

tip of the plumule, for the length of about an inch, was 
cotited with oil thickened with chalk, or when by any 
means this part of the plant was withdrawn from contact 
with free oxygen, the seedling ceased to grow, withered, 
and shortly perished. Traube observed the elongation 
of the stem by the following expedient. 

A young pea-plant was fastened by the cotyledons to a 
rod, and the stem and rod were both graduated by deli- 
cate cross-lines, laid on at equal intervals, by means of a 
brush dipped in a mixture of oil and indigo. The 
growth of the stem was now manifest by the widening of 
the spaces between the lines ; and, by comparison with 
those on the rod, Traube remarked that no growth took 
place at a distance of more than ten to twelve lines from 
the base of the terminal bud. 

Here, then, is a coincidence which appears to demon- 
strate that free oxygen must have access to a groT^^ing 
part. The fact is further shown by varnishing one side 
of the stem of a young pea. The varnished side ceases 
to extend, the uncoated portion continues enlarging, 
which results in a curvature of the stem. 

Traube further indicates in what manner the elabora- 
tion of cellulose from sugar may require the co-operation 
of oxygen and evolution of carbon dioxide, as expressed 
by the subjoined equation. 

aiuoose. Oxygen. Carbon dioxide. Water, CeUnlose. 

2 (CiaUj^Ui^) + 24 O = 12 (CO,) + 14 (H,0) + C^.tU^^Oxo- 

When tlie act of germination is finished, which occurs 
as soon as the cotyledons and endosi)erm are exhausted 
of all their soluble matters, the plant begins a fully inde- 
pendent life. Previously, however, to being thus thrown 
upon its own resources, it has developed all the organs 
needful to collect its food from without ; it has unfolded 
its perfect leaves into the atmosphere, and pervaded a 
portion of soil with its rootlets. 



3GG HOW CHOPS GROW. 

During tlie latter stages of germination it gathers its 
nutriment both from tlie parent seed and from the exter- 
nal sources which afterward serve exclusively for its 
support. 

Being fully provided with the apparatus of nutrition, 
its development suifers no check from the exhaustion of 
the mother seed, unless it has germinated in a sterile 
soil, or under other conditions adverse to vegetative life. 



CHAPTER II. 

THE FOOD OF THE PLANT WHEN INDEPENDENT OF THE 

SEED. 

This subject will be sketched in this place in but the 
briefest outlines. To present it fully would necessitate 
entering into a detailed consideration of tlie Atmosphere 
and of the Soil, whose rehitions to the Phint, tliose of the 
soil especially, are very numerous and complicated. A 
separate volume is therefore required for the adequate 
treatment of tliese topics. 

Tlie lioots of a plant, Avliich are in intimate contact 
with the soil, absorb thence the water that fills the active- 
cells ; they also imbibe such salts as the water of the soil 
holds in solution ; they likoAvise act directly on the soil, 
and dissolve substances, which are thus first made of 
avail to them. The compounds that the plant must 
derive from the soil are those which are found in its ash, 
since these are not volatile, and cannot, therefore, exist 
in the atmosphere. The root, however, commonly takes 



FOOD AFTER GEEMIMATIOI?". 3G7 

up some other elements of its nutrition to which it has 
immediate access. Leaving out of view, for the present, 
those matters which, though found in the plant, appear * 
to be unessential to its growth, viz., silica and sodium 
salts, the roots absorb the following substances, viz. : 

Sulphates "^ f Potassium, 

I'liosphates I f J Calcium, 

Nitrates a:id | 1 Magnesivini and. 

Clilorides J t Ii'on. 

These salts enter the plant by the absorbent surfaces 
of the younger rootlets, and pass upwards, through the 
stem, to the leaves and to the new-forming buds. 

The Leaves, which are unfolded to the air, gather 
from it Carbon dioxido Gas. This compound suffers 
decomposition in the plant ; its Carbon remains there, 
its Oxygen or an equivalent quantity, veiy nearly, is 
tlirown off into the air again. 

The decomposition of carbon dioxide takes place only 
by day and under the influence of the sun's light. 

From the carbon thus acquired and the elements of 
water with the co-operation of the ash-ingredients, the 
plant organizes the Carbhydrates. Probably some of the 
glucoses are the first products of this synthesis. Starch, 
in the form of granules, is the first product that is 
recognizable by help of the microscope. 

The formation of carbhydrates appears to proceed in 
the chlorophyl-cells of the leaf, where starch-granules 
first make their appearance. 

The Albuminoids require for their production the 
presence of a compound of Nitrogen. Tlie salts of 
Nitric Acid (nitrates) are commonly the chief, and may 
be the only, supply of this element. 

The other proximate principles, the fats, the alkaloids, 
and the acids, are built up from the same food-elements. 
In most cases the steps in the construction of organic 
matters are unknown to us, or subjects of uncertain con- 
jecture. 



368 now CRors grow. 

The cai'bhydratcs, albuminoids, etc., tliat are organ- 
ized in the foliage, are not only transformed into the 
solid tissues of the leaf, but descend and diffuse to every 
active organ of the plant. 

The plant has, within certain limits, a power of select- 
ting its food. The sea-weed, as has been remarked, 
contains more potash than soda, although the latter is 
30 times more abundant than the former in the water of 
the ocean. Vegetation cannot, however, entirely shut 
out either excess of nutritive matters or bodies that are 
of no use or even poisonous to it. 

The functions of the Atmosphere are essentially the 
same towards plants, whether growing under the con- 
ditions of water-culture or under those of agriculture. 

The Soil, on the other hand, has offices which are pe- 
culiar to itself. We have seen that the roots of a plant 
have the power to decompose salts, e. g., potassium 
nitrate and ammonium chloride (p. 184), in order to 
appropriate one of their ingredients, the other being 
rejected. In water-culture, the experimenter must have 
a care to remove the substance which would thus accu- 
mulate to the detriment of the plant. In agriculture, 
the soil, by virtue of its chemical and physical qualities, 
commonly renders such rejected matters comparatively 
insoluble, and therefore innocuous. 

The Atmosphere is nearly invariable in its composi- 
tion at all times and over all parts of the earth's surface. 
Its power of directly feeding crops has, therefore, a nat- 
ural limit, which cannot be increased by art. 

The Soil, on the other hand, is very variable in com- 
position and quality, and may be enriched and improved, 
or deteriorated and exhausted. 

From the Atmosphere the crop can derive no appreci- 
able quantity of those elements that are found in its 
Ash. 

In the Soil, however, from the waste of both plants 



MOTION OF THE JUICES. 3C9 

and animals, may acciimnlate large sniiplics of all tlie 
elements of the Volatile part of Plants. Carbon, cer- 
tainly in the form of carbon dioxide, probably or possi- 
bly in the condition of Humus (Vegetable Mold, Swamp 
Muck), may thus be put as food, at the disposition 
of the plant. Nitrogen is chiefly furnished to crops by 
the soil. Nitrates are formed in the latter from various 
sources, and ammonia-salts, together with certain proxi- 
mate animal principles, viz., urea, guanin, tyrosin, uric 
acid and hippuric acid, likewise serve to supply nitrogen 
to vegetation and are often ingredients of the best ma- 
nures. It is, too, from the soil that the crop gathers all 
the Water it requires, which not only serves as the fluid 
medium of its chemical and structural metamorphoses, 
but likewise must be regarded as the material from which 
it mostly appropriates the Hydrogen and Oxygen of its 
solid components. 



§2. 



THE JUICES OF THE PLANT, TIIEIH NATURE AND 

I MOVEMENTS. 

Very erroneous notions have been entertained with 
regard to the nature and motion of sap. It was formerl}^ 
taught that there are two regular and opposite currents 
of sap circulating in the plant. It was stated that the 
*^ crude sap" is taken up from the soil by the roots, 
ascends through the vessels (ducts) of the wood, to the 
leaves, there is concentrated by evaporation, ^^elabor- 
ated" by the processes that go on in the foliage, and 
thence descends through the vessels of the inner bark, 
nourishing these tissues in its way down. The facts 
from which this theory of the sap naturally arose admit 
of a very different interpretation ; while numerous con- 
24 



370 now cRorR onow. 

siderations dcmonRtr.itc the essential falsity of the tbeory 
itself. 

Flow of Sap in the Plant — not Constant or 
Necessary. — We speak of the Flow of Sap as if a rapid 
current were incessantly streaming through the plant, 
as the blood circulates in the arteries and veins of an ani- 
mal. This is an erroneous conception. 

A maple in early March, without foliage, with its 
whole stem enveloped in a nearly impervious bark, its 
buds wrapped np in horny scales, and its roots sur- 
rounded by cold or frozen soil, cannot be supposed to have 
its sap in motion. Its juices must be nearly or abso- 
lutely at rest, and when sap runs cojuously from an ori- 
fice made in the trunk, it is simply because the tissues 
are charged with water under pressure, which escapes at 
finy outlet that may be opened for it. The sap is at rest 
until motion is caused by a perforation of the bark and 
new wood. So, too, when a plant in early leaf is situa- 
ted in an atmosjihere charged witli moisture, as happens 
on a rainy day, there is little motion of its sap, nlthough, 
if wounded, motion may be established, and water may 
stream more or less from all parts of the plant towards 
the cut. { 

Sap does move in the plant when evaporation of water 
goes on from the surface of the foliage. This ahvays 
happens whenever the air J8 not saturated with vapor. 
When a wet cloth hung out, drieTsfapidly^T^y giving up 
its moisture to the air, then the leaves of plants lose 
their water more or less readily, according to the nature 
of the foliage. 

Mr. Lawes found that in the moist climate of England 
common plants (Wheat, Barley, Beans, Peas, and Clover) 
exhaled, during five months of growth, uiore than 200 
times their (dry) weight of water. Ilellriegel, in the 
drier climate of Dahme, Prussia, observed exhalation to 
average 300 times the dry weight of various common 



MOTTOT^ OF THE JUICES. 371 

crops (p. 312). Tlio water that thus evaporates from the 
lca,YC3 is supplied by the soil, and, entering the roots, 
more or less rapidly streams upwards through the stem as 
long as a waste is to be supplied, but this flow ceases 
when evaporation fiom the foliage is suppressed. 
^ The upward motion of sap is therefore to a great de- / . 
""gretit independent of the vital processes, and compara- . K 
tively unessential to the welfare of the plant. 

Flow of Sap from the Plant; " Bleeding."— It 
is a familiar fact, that from a maple tree " tapped " in 
spring-time, or from a grape-vino wounded at the same 
season, a copious flow of sap takes place, v/hich continues 
for a number of weeks. The escape of lirpdd froui the 
vine is commonly termed '^ bleeding," and while this 
rapid issue of sap is thus strikingly exhibited in compar- 
atively few cases, bleeding appears to be a univers il i^lie- 
nomenon, one that may occur, at least, to some degree, 
under certain conditions with very many plants. 

The conditions under which sap flows arc various, 
according to the character of the plant. Our perennial 
trees have their aunual period of active growth in the 
warm season, and their vegetative functions are nearly 
suppressed during cold weather. As spring approaches 
the tree renews its growth, and the first evidence of 
change within is furnished by its bleediugwhcn an opeu- 
ing is made through the bark into the young wood. A 
maple, tapped for making sugar, loses nothing until the 
spring warmth attains a certain intensity, and then sap 
begins to flow from the wounds in its trunk. The flow 
is not constant, but fluctuates with the thermometer, 
being more copious vvdien the weather is warm, and fall- 
ing off or suffering check altogether as it is colder. 

The stem of the living maple is always charged with 
water, and never more so than in winter.* This water 



* Experin*ients made in Tliarand, Saxony, Tinder direction of Ptoeok- 
hardt, show that the iiroportion of water, both in the bark and wood 



372 now CROPS grow. 

is cither jiumped into the plant, so to speak, by tlio root- 
power already noticed (p. 2G9), or it is generated in 
the trunk itself. The water contained in the stem in 
winter is undoubtedly that raised from the soil in the 
autumn. That which first flows from an auger-hole, in 
March, may be sim2:>ly what was thus stored in the trunk ; 
but, as the esca|)e of sap goes on for 1-i to 20 days at tlie 
rate of several gallons per day from a single tree, new 
quantities of water must be continually supplied. That 
these are pumped in from the root is, at first thouglit, 
difficult to understand, because, as we have seen (p. 272), 
the root-power is suspended by a certain low tempera- 
ture (unknown in case of the maple), and the flow of 
sap often begins when the ground is covered witli one or 
two feet of snow, and when we cannot suppose the soil 
to have a higher temperature than it had during the pre- 
vious winter months. Nevertheless, it must be that the 
deeper roots are warm enough to be active all the winter 
through, and that they begin their action as soon as the 
trunk acquires a temperature sufficiently high to admit 
the movement of water in it. That water may be pro- 
duced in the trunk itself to a slight extent is by no 
means impossible, for chemical changes go on there in 
spring-time with much rapidity, whereby the sugar of 
the sap is formed. These changes have not been suffi- 
ciently investigated, however, to prove or disprove the 
generation of water, and we must, in any case, assume 
that it is the root-power which chiefly maintains a pres- 
sure of liquid in the tree. 

The issue of sap from the maple tree in the sugar- 
season is closely connected with the changes of tempera- 
ture that take place above ground. The sap begins to 



of trees, varies considerably in different seasons of the year, ranpriner, 
in case of the beech, from 35 to 49 per cent of the fresh-feUed tree. The 
fjreatest proportion of water in the wood was found in the months of 
December and January ; in the l)arl<:, in Marcli to May. Tlie minimum 
of Avater in the wood 'occurred in May, June, and July; in the bai-k, 
much irregularity was observed. Chem. Ackersmann, 18CG, p. 159. 



MOTION OF THE JUTCES. 373 

flow from a, cut when the trunk itself is warmed to a cer- 
tain point and, in general, the flow appears to be the 
more rapid the warmer the trunk. During warm, clear 
days, the radiant heat of the sun is absorbed by the dark, 
rough surface of the tree most abundantly ; then the 
temperature of the latter rises most speedily and acquires 
the greatest elevation — even surpasses that of the atmos- 
phere by several degrees ; then, too, the yield of sap is 
most copious. On clear nights, cooling of the tree takes 
place with corresponding rapidity ; then the snow or 
surface of the ground is frozen, and the flow of sap is 
checked altogether. From trees that have a sunny ex- 
posure, sap runs earlier and faster than from those hav- 
ing a cold northern aspect. Sap starts sooner from the 
spiles on the south side of a tree tlian from those towards 
the north. 

Duchartre {CWiptes Rendus, IX, 754) passed a vine 
situated in a grapery, out of doors, and back again, 
through holes, so that a middle portion of the stem was 
exposed to a steady winter temperature ranging from 18° 
to 10° F., while the remainder of the vine, in the house, 
was surrounded by an atmosphere of 70° F. Under 
these circumstances the buds within develoj^ed vigor- 
ously, but those without remained dormant and opened 
not a day sooner than buds upon an adjacent vine whose 
stem was all out of doors. That sap passed through the 
cold part of the stem was shown by the fact that the 
interior shoots sometimes wilted, but again recovered 
their turgor, which could only happen from the partial 
suppression and renewal of a sup})ly of water through the 
stem. Payen examined the wood of the vine at the con- 
clusion of the experiment, and found the starch which it 
originally contained to have been equally removed from 
the warm and the exposed parts. 

That the rate at which sap passed through the stem 
was influenced by its temperature is a plain deduction 



374 now CROPS gro-w. 

from the fact that the leaves within were found wilted 
in the morning, while they recovered toward noon, al- 
though the temperature of the air without remained 
below freezing. The wilting was no doubt chiefly due 
to the diminished power of the stem to transmit water ; 
the return of the leaves to their normal condition was 
probably the consequence of the warming of the stem by 
the sun's radiant heat.* 

One mode in which changes of temperature in the 
trunk influence the flow of sap is very obvious. The 
wood-cells contain, not only water, but air. Both are 
expanded by heat, and both contract by cold. Air, 
especially, undergoes a decided change of bulk in this 
way. Water expands nearly one-twentieth in being 
warmed from 32° to 2L2°, and air increases in volume 
more than one-third by the same change of temperature. 
When, therefore, the trunk of a tree is warmed by the 
sun's heat, the air is expanded, exerts a pressure on the 
sap, and forces it out of any wound made through the 
bark and wood-cells. It only requires a rise of tempera- 
ture to the extent of a few degrees to occasion from this 
cause alone a considerable flow of sa^) from a large tree. 
(Hartig.) 

If we admit that water continuously enters the deep- 
lying roots whose temperature and absorbent pov»^er must 
remain, for the most part, invariable from day to day, 
we should have a constant slow escape of sap from the 
trunk were the temperature of the latter uniform and 
sufliciently high. This really happens at times during 
everv sugar-season. When the trunk is cooled down to 
the freezing point, or near it, the contraction of air and 
water in the tree makes a vacuum there, sap ceases to 
flow, and air is sucked in through the spile ; as the trunk 



* The temperatnre of the air is not always a sure infUcation of that 
of the soUfl bodies whicli it surrounds. A thormonieter will often ripe 
by exposure of the bulb to the direct rays of the sun, 30 or 40"^ above its 
indications when in tlie shade. 



MOTION OF THE JUICES. 375 

becomes heated again, the gaseous and liquid contents of 
tiie ducts expand, the flow of sap is renewed, and pro- 
ceeds Avith increased rapidity until the internal pressure 
passes its maximum. 

As the season advances and the soil becomes heated, 
the rooc-power undoubtedly acts with increased vigor 
and larger quantities of water are forced into the trunk, 
but at a certain time the escape of sap from a wound 
suddenly ceases. At this period a new phenomenon 
supervenes. The buds which were formed the previous 
summer begin to expand as the vessels are distended with 
sap, and finally, wlien the temperature attains the proper 
range, they unfold into leaves. At this point we have 
a proper motion of sap in the tree, whereas before there 
was little motion at all in the sound trunk, and in the 
tapped stem the motion was towards the orifice and 
thence out of the tree. 

The cessation of flow from a cut results from two cir- 
cumstances : first, the vigorous cambial growth, where- 
by incisions in the bark and wood rapidly heal up ; and, 
second, the extensive evaporation that goes on from 
foliage. 

That evaporation of water from the leaves often pro- 
ceeds more rapidly than it can be sup])lied by the roots 
is shown by the facts that the delicate leaves of many 
plants wilt when the soil about their roots becomes dry, 
that water is often rapidly sucked into wounds on the 
stems of trees which are covered with foliage, and that 
the proportion of water in the wood of the trees of tem- 
perate latitudes is least in the months of May, June, and 
July. 

Evergreens do not bleed in the spring-time. The oak 
loses little or no sap, and among other trees great diver- 
sity is noticed as to the amount of water that escapes at 
a wound ou the stem. In case of evergreens we have a 
stem destitute of all proper vascular tissue, and admit- 



376 HOW CHOPS GROW. 

ting a flow of liquid only througli perforations of the 
wood-cells, if these really exist (which Sachs denies). 
Again, the leaves admit of continual evaporation, and 
furnish an outlet to the water. The colored heart-wood 
existing in many trees is impervious to water, as shown 
by the experiments of Boucherie and Hartig. Sap can 
only flow through the white, so-called sap-wood. In 
early June, the new shoots of the vine do not bleed when 
cut, nor does sap flow from the wounds made by break- 
ing them off close to the older stem, although a gash in 
the latter bleeds profusely. In the young branches, 
there are no channels that permit the rapid efiiux of 
water. 

Composition of Sap. — The sap in all cases consists 
cliiefly of water. This liquid, as it is absorbed, brings 
in from the soil a small proportion of certain saline mat- 
ters — the phosphates, sulphates, nitrates, etc., of potas- 
sium, calcium, and magnesium. It finds in the plant 
itself its organic ingredients. These may be derived 
from matters stored in reserve during a previous year, as 
in the spring sap of trees ; or may be newly formed, as 
in summer growth. 

The sugar of maple-sap, in spring, is undoubtedly pro- 
duced by the transformation of starch which is found 
abundantly in the wood in winter. According to Hartig 
{Jour, far FraJct. Oh., 5, p. 217, 1835), all deciduous 
trees contain starch in their wood and yield a sweet 
spring sap, while evergreens contain little or no starch. 
Ilartig reports having been able to i)rocure from the root- 
wood of the horse-chestnut in one instance no less than 
2G per cent of starch. This is deposited in the tissues 
durinir summer and autumn, to be dissolved for the use 
of the plant in developing new foliage. In evergreens 
and annual plants the organic matters of the sap are 
derived more directly from the foliage itself. The leaves 
absorb carbon dioxide and unite its carbon to the ele- 



MOTION OF THE JUICES. 377 

ments of water, with the production of sugar and otherp^ J 
carbhydrates. In the leaves, also, probably nitrogen 
from the nitrates and ammonia-salts gathered by the 
roots, is united to carbon, hydrogen, and oxygen, in the 
formation of albuminoids. 

Besides sugar, malic acid and minute quantities of 
proteids exist in maple sap. Towards the close of the 
sugar-season the sap appears to contain other organic 
substances which render the sugar impure, brown in 
color, and of different flavor. 

It is a matter of observation that maple-sugar is whiter, 
purer, and " grains " or crystallizes more readily in those 
years when spring-rains or thaws are least frequent. 
This fact would appear to indicate that the brown or- 
ganic matters which water extracts from leaf-mold may 
enter the roots of the trees, as is the belief of practical 
men. 

The spring-sap of many other deciduous trees of tem- 
perate climates contains sugar, but while it is cane sugar 
in the maple, in other trees it appears to consist mostly 
or entirely of dextrose. 

Sugar is the chief organic ingredient in the juice of 
the sugar cane, Indian corn, beet, carrot, turnip, and 
parsnip. 

The sap that flows from the vine and from many cul- 
tivated herbaceous plants contains little or no sugar ; in 
that of the vine, gum or dextrin is found*in its stead. 

What has already been stated makes evident that we 
cannot infer the quantity of sap in a plant from what 
may run out of an incision, for the sap that thus issues 
is for the most part water forced u]) from the soil. It is 
equally plain that the sap, thus collected, has not the 
normal composition of the juices of the plant; it must 
be diluted, and must be the more diluted the longer and 
the more rapidly it flows. 

Ulbricht has made partial analyses of the sap obtained 



o78 now CROPS GROW. 

from the stumps of potato, tol)iicGo, and siiii^ flower 
plants. He found that successive portions, collected 
separately, exhibited a decreasing concentration. In 
sunflower saj), gathered hi five successive portions, the 
liter contained the following quantities (grams) of solid 
matter : 

1. 2. 3, 4. 5. 

Volatile substance,... 1.45 O.GO 0.30 0.25 0.21 

Ash, .1.58 1.5G 1.18 0.70 O.GO 



Total...... 3.03 2.1G 1.48 O.'JS 0.81 

The water which streams from a wound dissolves and 
carries forward with it matters that, in the uninjured 
plant, would jirobahly suffer a much less rapid and ex- 
tensive translocation. From the stump of a potato-stalk 
would issue, by the mere mechanical elfect of the flow of 
water, substances generated in the leaves, whose proper 
movement in the uninjured plant would be downwards 
into the tubers. 

Different Kinds of Sap. — It is necessary at this 
point in our discussion to give prominence to the fact 
that there are dillerent kinds of sap in the plant. As 
we have seen (p. 289), the cross section of the plant pre- 
sents tv;^o kinds of tissue, the cellular and vascular. 
Tliese carry different juices, as is shown by their chemi- 
cal reactions. In the cell-tissues exist chiefly tlie non- 
nitrogenous principles, sugar, starch, oil, etc. The 
liquid in these cells, as Sachs has sliown, commonly con- 
tains also organic acids and acid-salts, and hence gives a 
red color to blue litmus. In the vascular tissue albumin- 
oids preponderate, and the sap of the ducts commonly 
has an alkaline reaction towards test papers. These dif- 
ferent kinds of sap are not, however, always strictly con- 
fined to either tissue. In the root-tips and buds of 
many plants (maize, squash, onion), the young (new- 
formed) cell-tissue is alkaline from the preponderance of 



M3TI02^ OF TKE JUICES. 379 

albuminoids, while the spring sap flowing from tho ducts 
and wood of the maple is faintly acid. 

In many plants is found a system of channels (milk- 
ducts, p. 304), independent of the vascular bundles, 
which contain an opaque, white, or yellow juice. This 
liquid is seen to exude from the broken stem of the milk- 
weed (Asclepias), of lettuce, or of celandine {Chelidoji- 
ium)y and may be noticed to gather in drops vipon a 
fresh-cut slice of the sweet potato. The milky juice 
often differs, not more strikingly in appearance than it 
docs in taste, from the transparent sap of the cell-tissue 
and vascular bundles. The former is commonly acrid 
and bitter, while the latter is sweet or simply insipid to 
the tongue. 

Motion of the Nutrient Matters of the Plant. — 
The occasional rapid passage of a current of water u in- 
wards through the plant must not be confounded with 
the normal, necessary, and often contrary motion of the 
nutrient matters out of which nev/ growth is organized, 
but is an independent or highly subordinate process by 
which the plant adapts itself to the constant changes 
that arc taking place in the soil and atmosphere as re- 
gards their content of moisture. 

A plant supidied with enough moisture to keep its tis- 
sues turgid is in a normal state, no matter whether the 
water within it is nearly free from upward flow or ascends 
rapidly to compensate the wiiste by evaporation. In 
both cases the motion of the matters dissolved in the sap 
is nearly the same. In both cases the plant develops 
nearly alike. In both cases the nutritive matters gath- 
ered at tho root-tips ascend, and those gathered by the 
leaves descend, being distributed, to every growing cell; 
and these motions are comparatively independent of, and 
but little influenced by, the motion of the water in which 
they are dissolved. 

The upward ^oz^ of sap in the plant is confined to the 



380 UOW CHOI'S GliOW. 

vasciiliir biiiidlcs, whether these are arranged symmetric 
cally and comp.iotly, as in exogenous plants, or distrib- 
uted singly through the stem, as in the endogens. This 
is not only seen upon a bleeding stump, but is made evi- 
dent by the oft-observed fact tnat colored liquids, when 
absorbed into a plant or cutting, visibly follow the course 
of the vessels, though they do not commonly penetrate 
the spiral ducts, but ascend in the sieve-cells ot the cam- 
bium.* 

The rapid supply of water to the foliage of a plai.t, 
either from the roots or from a vessel in wiiich the cut 
stem is immersed, goes on when the cellular tissues of 
the bark and pith are removed or intcrrui)ted, but is at 
once checlvcd by severing the vascular bundles. 

The proper motion of the nutritive matters in the 
plant — of the salts disssolved from the soil and of the 
organic principles comjiounded from carbonic acid, water, 
and nitric aoid or ammonia in the leaves — is one of sloio 
difusion, mostly through the walls of imperforate cells, 
and goes on in all directions. New growth is the forma- 
tion and expansion of new cells into which nutritive 
substances arc imbibed, but not poured through visible 
passages. When closed cells are converted into ducts or 
visibly communicate with each other by pores, their ex- 
pansion has ceased. Henceforth they merely become 
thickened by interior deposition. 

Movements of Nutrient Matters in the Bark or 
Rind. — The ancient observation of what ordinarily ensues 
Avhen a ring of bark is removed from the stem of an exo- 
genous tree, led to the erroneous assumption of a form= 
al downward current of ^' elaborated " sap in the bark. 
When a cutting from one of our common trees is girdled 
at its midille and then placed in circumstances favorable 



* As in T^iuTor's oxperlmont, of y^lafincr a livarinth in tlio juice of t]ie 
polvH wof'd ( l'byt(>)nrc<i\ or in HaUier'y observations on cuttings tLpped 
in cherry-juice. ( Tii. >SY., IX, p. 1.) 



MOTIOiq" OF THE JUICES. 



381 




Fi^i. 6fi. 



for growth, as in moist, warm 
air, with its lower extremity 
in water, roots form chiefly 
at the edge of the bark just 
above the removed ring. The 
twisting, or half-breaking, as 
well as ringing of a layer, 
promotes the development of 
roots. Lutent buds are often 
called forth on the stems of 
fruit trees, and branches grow 
more vigorously, by making 
a transverse incision through 
the bark just below the point 
of their issue. Girdling a 
fruit-bearing branch of the 
grape-vine near its junction 
with the older wood has the 
eifect of greatly enlarging the 
fruit. It is well known that 
a wide wound made on the 
stem of a tree heals up by tlie 
formation of new wood, and 
commonly the growth is most 
rapid and abundant above the 
cut. From these facts it was 
concluded that sap descends 
in the bark, and, not being 
able to pass below a wound, 
leads to the organization of 
new roots or wood just above 
it. 

The accompanying Uhistration, 
Fig. CG, represents the base of a cut- 
ting from an exogenous stem (pear 
or currant), girdled at B and kept 
for some days immersed in water to 
the depth indicated by tlic line L. 



382 HOW CROPS GROW. 

The first maif estation of growth is the formation of a protuberance at 
the lower edge of the banc, which is known to gardeners as a callous, 
C. Tliis is an extension of tlie cellular tissue. From the callous shortly 
appear rootlets, li, which originate from the vascular tissue. Rootlets 
also break from the stem above the callous and also above the water, 
if the air be moist. They appear, likcAvise, though in less number, 
below the girdled place. 

Nearly all the organic substances (carbhydratcs, al- 
buminoids, acids, etc.) that are formed in a plant are 
produced in the leaves, and must necessarily find their 
way down to nourish the stem and roots. The facts 
just mentioned demonstrate, indeed, that they do go 
down in the bark. We have, however, no proof that 
there is a downward flow of sap. Such a flow is not 
indicated by a single fact, for, as we have before seen, 
the only current of water in the uninjured plant is the 
upward one which results from root-action and evapora- 
tion, and that is variable and mainly independent of the 
distribution of nutritive matters. Closer investigation 
has shown that the ?nost ahundant downward movement 
of the nutrient matters generated in the leaves proceeds 
in the thin-walled sieve-cells of the cambium, which, in 
exoo-ens, is young tissue common to the outer wood and the 
inner bark — which, in fact, unites bark and wood. The 
tissues of the leaves communicate directly with, and are 
a continuation of, the cambium, and hence matters 
formed by the leaves must move most rapidly in the 
cambium. If they pass with greatest freedom through 
the sieve-cells, the fact is simply demonstration that the 
latter communicate most directly with those parts of the 
leaf in which the matters they conduct are organized. 

In endogenous plants and in some exogens {Pi^m- me- 
dium, Amarantlms sanguineus), the vascular bundles 
containing sieve-cells pass into the pith and are not con- 
fined to the exterior of the stem. Girdling such plants 
does not give the result above described. With them, 
roots are formed chiefly or entirely at the base of the 
cutting (Hanstein), and not above the girdled place. 



MOTIOIT OF TITE JUICES. 383 

In all cases, without exception, tlio matters organized 
in the leaves, though most readily and abundantly mov- 
ing downwards in the vascular tissues, are not confined 
to them exclusively. When a ring of bark is removed 
from a tree, the new cell-tissues, as well as the vascular, 
are interrupted. Notwithstanding, matters are trans- 
mitted downwards, through the older wood. When but 
a narro2u ring of bark is removed from a cutting, roots 
often appear below the incision, though in less number, 
and the new growth at the edges of a wound on the 
trunk of a tree, though most copious above, is still de- 
cided below — goes on, in fact, all around the gash. 

Botli the cell-tissue and the vascular thus admit of 
the transport of the nutritive matters downwards. In 
the former, the carbhydratas — starch, sugar, imihn — the 
fats, and acido, chiefly occur and move. In the large 
ducts, air is contained, except when by vigorous root- 
action the Gtem is surcharged with wacer. In the sieve- 
ducts (cambium) are found the albumiuoidrj, though not 
unmixed with curbhydrates. If a tree have a deep gash 
cut into its stem (but not reaching to the colored heart- 
wood), growth is not suppressed on eitlier side of the 
cut, but the nutritive matters of all kinds pr.ss out of a 
vertical direction around the incision, to nourish tlie new 
wood above and below. Girdling a tree is not fatal, if 
done in the spring or early summer when growth is rapid, 
provided Viiit the young cells, which form externally, 
are protected from dryness and other destructive influ- 
ences. An artificial bark, i. e., a covering of cloth or 
clay to keep the exposed wood moist and away from air, 
saves the tree until the Avound heals over.* In these 
cases it is obvious that the substances which commonly 
preponderate in the sieve-ducts must pass through the 



* If the froshlv expc^ert wood be nibbed or wiped with a cloth, 
whereby the moist oambial layer (of cells containing nuclei and capa- 
ble of multiplying) is removed, no growth can occur. Eatzeburg. 



384 HOW CROPS GROW. 

cell-tissne in order to reach the point where they nourish 
the growing organs. 

Evidence that nutrient matters also pass upivards in 
the hiii'k is furnished, not only hy ti-acing the course of 
colored liquids in the stem, hut also by the fact that 
un.developed buds perisli in most cases when the stem is 
girdled between them and active leaves. In the excep- 
tions to tliis rule, the vascular bundles penetrate the 
])iih, and thereby dcmonslrate that they are the chan- 
nels of this movement. A nnnoricy of these exceptions 
agdn makes evident that the sJeve-cells are the path of 
transfer, for, as Hanstein has shov/n, in certain plants 
(Solanaceas, AsclepiadcEe, etc.), sieve-cells penetrate the 
pith unaccompanied by any other elements of the vascu- 
lar bundle, and girdled twigs of these plants grow above 
as well as beneath the wound, although all leaves above 
the girdled place be cut off, so that the nutriment of the 
buds must come from belov/ the incision. 

The substances which are organized in the foliage of a 
plant, as well as those which are imbibed by the roots, 
move to any point where they can supply a want. Carb- 
hydrates pass from the leaves, not only downwards, to 
nourish new roots, but upwards, to feed the buds, flow- 
ers, and fruit. In case of cereals, the power of tlie 
leaves to gather and organize atmospheric food nearly or 
altogetlier ceases as they approach maturity. The seed 
grows at the expense of matters previously stored in the 
foliage and stems (p. 237), to such an extent that it may 
ripen quite perfectly although the plant be cut when the 
kernel is in the milk, or even earlier, while the juice of 
the seeds is still watery and before starch-grains have 
begun to form. 

In biennial root-crops, the root is the focus of motion 
for the matters organized by growth during the first 
year ; but in the second year the stores of the root are 
completely exhausted for the support of flov;ers and seed. 



CAUSES OF THE MOTIOJf OF JUICES. 385 

SO that the direction of the movement of tliese organized 
matt.TS is reversed. In both years the motion of neater 
is always the same, viz., from the soil upv/ards to the 
leaves.* 

The summing np of tlie whole mattc^r is that the nutri- 
ent sdbsfcances in the plant are not absolutely confined 
to any patli, and may move in any direction. Tiie fact 
that they chiefly follow certain channels, and move m 
this or that direction, is plainly dependent upon die 
structure and arrangement of the tissues, on the sources 
of nutriment, and on the seat of growth or otiier action. 



3. 



THE CAUSES OF MOTIOJ?" OF THE VEGETABLE JUICES. 

Porosity of Vegetable Tissues. — Porosity is a 
property of all the vegetable tissues and implies that the 
molecules or smallest particles of matter comiiosing the tis- 
sues are separated from each other by a certain sjiace. In 
a multitude of cases bodies are visibly porous. In many 
more we can see no pores, even by the aid of the highest 
magnifying powers of the microscope ; nevertheless the 
fact of porosity is a necessary inference from another 
fact which may be observed, viz., that of absorption. A 
fiber of linen, to the unassisted eye, has no pores. 
Under the microscope we find that it is a tubular cell, 
the bore being much less than the thickness of the walls. 
By immersing it in water it swells, becomes -more trans- 
parent, and increases in weight. If the water be colored 
by solution of indigo or cochineal, the fiber is visibly 

* The motion of water is always upwards, because the soil always 
contains more water than the air. If a plant were so situated that its 
roots should steadily lack water while its foliatje had an excess of this 
liquid, it cannot be doubted that then the "sap " would pass down in 
a regular flow. In this case, nevertheless, the nutrient matters would 
take their normal course. 

25 




386 HOW CROPS GROW. 

penetrated by the clye. It is therefore porous, not only 
in the sense of having fin interior cavity which becomes 
visible by a high magnifying power, but likewise in hav- 
ing throughout its a2)parently imperforate substance in- 
numerable channels in which liquids can freely pass. 
In like manner, all the vegetable tissues are more or less 
penetrable to watei*. 

Imbibition of Liquids by Porous Bodies. — Kot 
oniv do tlie tissues of the plant admit of the access of 
water into their pores, but Ihey forcibly drink in or 
aosoro tnis liquid, when it is presented to them in excess, 
until their pores are full. 

When the molecules of a porous body have freedom 
of motion, they separate from each other on imbibing a 
liquid ; the body itself swells. Even powdered glass or 
fine sand perceptibly increases in bulk by imbibing water. 
Clay swells much more. Gelatinous silica, pectin, gum 
tragacanth, and boiled starch hold a vastly greater amount i 
of water in their pores or among their molecules. 

In case of vegetable and animal tissues, or membranes, 
we find a greater or less degree of expansibility from the 
same cause, but here the structural connection of the 
molecules puts a limit to their separation, and the result 
of saturating them with a liquid is a state of turgidity 
and tension, which subsides to one of yielding flabbiness 
when the liquid is partially removed. 

The energy with which vegetable matters imbibe water 
may be gathered from a well-known fact. In granite 
quarries, long blocks of stone are split out by driving 
plugs of dry wood into holes drilled along the desired 
line of fracture and pouring water over the plugs. The 
liquid penetrates the wood with immense force, and the 
toughest rock is easily broken apart. 

The imbibing power of different tissues and vegetable 
matters is widely diverse. In general, the younger or- 
gans or parts take up water most readily and freely. The 



CAUSES OF THE MOTION 01? JUICES. 387 

sap-woofl of trees is far more absorbent than the heart- 
wood and bark. The cuticle of the leaf is often com- 
paratively impervious to water. Of the proximate ele- 
ments we have cellulose and starch-grains able to retain, 
even when air-dry, 10 to 15% of water. Wax and the 
solid fats, as well as resins, on the contrary, do not 
greatly attract water, and cannot easily be wetted with 
it. They render cellulose, which has been impregnated 
with them, unabsorbent. 

Those vegetable substances which ordinarily manifest 
the greatest absorbent power for water, are the gummy 
carbhydrates and the albuminoids. In the living plant 
the protoplasmic membrane exhibits great absorbent 
power. Of mineral matters, gelatinous silica (Exp. 58, 
p. 137) is remarkable on account of its attraction for 
water. 

Not only do diifercnt substances thus exhibit unlike 
adhesion to water, but the same substance deports itself 
variously towards different liquids. 

One hundred parts of dry ox-bladder were found by 
Liebig to absorb during 24 hours : — 

268 parts of pure Water. 

133 " " saturated Brine. 

38 " " Alcohol (84%). 

17 " " Bone-oil. 

A piece of dry leather will absorb either oil or water, 
and apparently with equal avidity. If, however, oiled 
leather be immersed in water, the oil is gradually and 
perfectly displaced, as the farmer well knows from his 
experience with greased boots. India-rubber, on the 
other hand, is impenetrable to water, while oil of tur- 
pentine is imbibed by it in large quantity, causing the 
caoutchouc to swell up to a pasty mass many times its 
original bulk. 

The absorbent power is influenced by the size of the 
pores. Other things being equal, the finer these are, the 
greater the force with which a liquid is imbibed. This 



388 HOW CROPS GROW. 

I 

is shown by wliiit has been learned from the study of a 
kind of pores whose effect admits of accurate measure- 
ment. A tube of glass, with a narrow, uniform caliber, 
is such a pore. In a tube of 1 millimeter (about 2^ of 
an inch), in diameter, water rises 30 mm. In a tube of 
-/^ millimeter, the liquid ascemls 300 mm. (about 11 
inches) ; and, in a tube of jJi, mm., a column of 3,000 
mm. is sustained. In porous bodies, like chalk, plaster 
stucco, closely packed ashes or starch, Jamin fonnd that 
water was absorbed with force enouo'h to overcome the 
pressure of the atmosphere from three to six times ; in 
other words, to sustain a column of water in a wide 
tube 100 to 200 ft. hi^i^h. {Compies Renclus, 50, p. 311.) 

Absorbent power is influenced by temperature. Warm 
water is absorbed by wood more quickly and abundantly 
than cold. In cold water starch does not swell to any 
r.triking or even perceptible degree, although consider- 
able liquid is imbibed. In hot water, however, the case 
is remarkably altered. The starch-grains are forcibly 
burst open, and a paste or jelly is formed that holds 
many times its weight of v/ater. (Exp. 27, p. 51.) On 
freezing, the particles of water are mostly withdrawn 
from their adhesion to the starch. The ascent of liquids 
in narrov/ tubes whoso walls arc unabsorbent, is, on the 
contrary, diminished by a rise of temperature. 

Adhesive Attraction.— The absorption of a liquid 
into the cavities of a porous body, as well as its rise in a 
narrow tube, are expressions of the general fact that 
there is an attraction between the molecules of the liquid 
and the solid. In its simplest manifestation this attrac- 
tion exhibits itself as Adhesion, and this term we siiall 
employ to designate the kind of force under considera- 
tion. If a clean plate of glass be dij^ped in water, the 
liquid touches, and sticks to, the glass. On withdraw- 
ing the glass, a film of water comes away with it — the 
adhesive force of water to glass being greater than the 
cohesive force amone: the water molecules. 



CAUSES OF THE MOTION OF JUICES. 389 

Capillary Attraction. — If two squares of glass be 
set np together iipDii a j^late, so that they shall be 
in contact at their Ycrtical etlges on one side, and one- 
eighth of an inch apart on the other, it will be seen, on 
pouring a little water upon the plate, that this liquid 
rises in the space between them to a hight of several 
inches where they are in very near proximity, and curves 
downwards to their base where the interval is large. 

Ccqnllary attraction, which thus causes liquids to rise 
in narrow channels or fine tubes, involves indeed the 
adhesion of the liquid to the walls of the tabe, but also 
depends on a tension of the surface of the liquid, due to 
the fact that the molecules at the surface only attract 
and are only attracted by underlying molecules, so that 
they exert a pressure on the mass of liquid beneath them. 
Where the liquid adheres to the sides of a containing 
tube or cavity, this j^ressure is diminished and there the 
liquid rises. 

Adhesion may be a Cause of Continual Move- 
ment under certain circumstances. When a new cotton 
wick is dipped into oil, the motion of the oil may be fol- 
lowed by the eye, as it slowly ascends, until the pores 
are filled and motion ceases. Any cause which removes 
oil from the pores at the apex of the wick will disturb 
the equilibrium which had been established between the 
solid and the liquid. A burning match held to the 
wick, by its heat destroys tlie oil, molecule after mole- 
cule, and this process becomes permanent when the wick 
is lighted. As the pores at the base of the flame give up 
oil to the latter, they fill themselves again from the 
pores beneath, and the motion thus set up propagates 
itself to the oil in the vessel below and continues as long 
as the Ikime burns or the oil holds out. 

We get a further insight into the nature of this motion 
when we consider what happens after the oil has all been 
sucked up into the wick. Shortly thereafter the dimen- 



390 HOW CROPS GKOW. 

sions of the flame are seen to dimmish. lb does not, 
however, go out, but burns on for a time with continually 
decreasing vigor. When the supply of liquid in the por- 
ous body is insufficient to saturate the latter, there is 
still the same tendency to equalization and equilibrium. 
If, at last, when the flame expires, because the combus- 
tion of tlie oil falls below that rate which is needful to 
geiiei-ate heat sufficient to decompose it, the wick be 
placed in contact at a single point, with another dry 
wick of equal mass and porosity, the oil remaining in 
the flrst will enter again into motion, will pass into the 
second wick, from pore to pore, until the oil has been 
shared nearly equally between them. 

In case of water contained in the cavities of a porous 
body, evaporation from the surface of the latter becomes 
remotely the cause of a continual upward motion of the 
liquid. 

The exhalation of water as vapor from the foliage of a 
plant thus necessitates the entrance of water as liquid 
at the roots, and maintains a flow of it in the sap-ducts, 
or causes it to pass by absorption from cell to cell. 

Liquid Diffusion. — The movements that proceed in 
plants, when exhalation is out of the question, viz., such 
as are manifested in the stump of a vine cemented into a 
gauge (Fig. 43, p. 248), are not to be accounted for by 
capillarity or mere absorptive force under the conditions 
as yet noticed. To approach their elucidation we require 
to attend to other considerations. 

The particles of many different kinds of liquids attract 
each other. Water and alcohol may be mixed together 
in all proportions in virtue of their adhe ive attraction. 
If we fill a vial with water to the rim and carefully lower 
it to the bottom of a tall jar of alcohol, we shall find 
after some hours that alcohol has penetrated the vial, 
and water has passed out into the jar, notwithstanding 
the latter liquid is considerably heavier than the former. 



CAUSES OF THE MOTION OF JUICES. 391 

If the water be colored by indigo or cherry juice, its 
motion may be followed by the eye, and after a certain 
lapse of time the water and alcohol will be seen to have 
become uniformly mixed throughout the two vessels. 
This manifestation of adhesive attraction is termed Liq- 
uid Diffusion. 

What is true of two liquids likewise holds for two 
solutions, i. e., for two solids made liquid by the action 
of a solvent. A vial filled with colored brine, or syrup, 
and placed in a vessel of water, will discharge its con- 
tents into the latter, itself receiving water in return ; 
and this motion of the liquids will not cease until the 
whole is uniform in composition, i. e., until every mole- 
cule of salt or sugar is equally attracted by all the mole- 
cules of water. 

When several or a large number of soluble substances 
are placed together in water, the diffusion of each one 
throughout the entire liquid will go on in the same way 
until the mixture is homogeneous. 

Liquid Diffusion may be a Cause of Continual 
Movement whenever circumstances produce continual 
disturbances in the composition of a solution or in that 
of a mixture of liquids. 

If into a mixture of two liquids we introduce a solid 
body which is able to combine chemically with, and 
solidify one of the liquids, the molecules of this liquid 
will begin to move toward the solid body from all points, 
and this motion will cease only when the solid is able to 
combine with no more of the one liquid, or no more 
remains for it to unite with. Thus, when quicklime is 
placed in a mixture of alcohol and water, the water is in 
time completely condensed in the lime, and the alcohol 
is rendered anjiydrous. 

Rate of Diffusion. — The rate of diffusion varies with 
the nature of the liquids ; if solutions, with their degree 
of concentration and with the temperature. 



392 HOW CROPS GROW. 

Colloids and Crystalloids. — There is a class of bodies 
whose molecules are singuhirly inactive in many respects, 
and have, when dissolved in water or other liquid, a 
very low capacity for diffusive motion. Tliese bodies 
are termed Colloids,'^ and are characterized by swelling 
np or uniting with water to bulky masses (hydrates) of 
gelatinous consiotence, by inability to crystallize, and by 
feeble and poorly-defined chemical affinities. Starch, 
dextrin, the gums, the albuminoids, pectin and pectic 
acid, gelarin (glue), tannin, the hydroxides of iron and 
aluminium and gelatinous silica, are colloids. 0[,posed 
to these, in the properties just specified, are those bodies 
which crystallize, such as saccharose, glucose, oxalic, 
citric, and tartaric acids, and the ordinary salts. 

Other bodies which have never been seen to crystallize 
have the same high diffusive rate ; hence the class is 
termed by Graham Crys!alloids.\ 

Colloidal bouios, when insoluble, are capable of imbib- 
ing liquids, and admit of liquid diffusion through their 
molecular intersi)aces. Insoluble crystalloids are, on 
the other hand, imi)enetrable to liciuids in this S':>nse. 
The colloids swell up more or less, often to a great Inilk, 
from abs()r])ing a liquid ; the volume of a crystalloid 
admits of no such change. 

In his study of the rates of diffusion of various sub- 
stances, dissolved in water to the extent of one per cent 
of the liquid, Graham f(nind the following 

APPUt)XIMATE TIMES OF EQUAL DIFFUSION. 

Hydrochloric acid, CrystaUoid, 1. 

Sodium Chloride, " 2J. 

Cane Sugar, '« 7. 

Magnesium Sulphate, " 7. 

Albumin, Colloid, 40. 

Caramel, " 98. 



* From two Greek words which signify gluc-Uke. 

t We have already em])loyed the word Cri/s/dUoid to distinguish the 
amorphous albuminoids from their nuxUlic-vtious or combinations 
wliicli i>reseut the aspect of crystals (p. 107). 'I'liis use of the woixi was 
proposed by Njigeli, in 18G2. Graham had emi)loyed it, as opposed to 
colloid, in iSGl. 



CAUSES OF THE MOTIOJS" OF JUICES. 393 

The table shows that the diffusive activity of hydro- 
chloric acid through water is 98 times as great as that of 
caramel (see p. G6, Exp. 29). In other words, a mole- 
cule of the acid will travel 98 times as far in a given 
time as the molecule of caramel. 

Osmose,* or Membrane Diffusion. — Yvhen two 
miscible liquids or solutions arc separated by a porous 
diaphragm, the phenomcua of diiiusion (which depend 
upon the mutual attraction of t!ie moleculcG of the dif- 
ferent liquids or dissolved substances) are complicated 
with those of imbibition or capillarity, and of chemical 
aflSnity. The adhesive or other force Vvdiich the Gepuiim 
is able to exert upon the liquid molecules supervenes 
upon the mere diffusive tendency, and the movements 
may suffer remarkable modilicatious. 

If we should separate pure water and a solution of 
common salt by a membrane upon whoso substance these 
liquids could exert no action, the diffusion would pro- 
ceed to the same result as were the membrane absent. 
Molecules of water v/ould p^netnite the membrane on 
one side and molecules of salt ovi the other, until the 
liquid should become alike on both. Should the water 
move faster than the salt, the volume of the brine would 
increase, and that of the water would correspondingly 
diminish. Were the membrane fixed in its place, a 
change of level of the liquids would occur. Graham has 
observed that common salt actually diffuses into v/ater, 
through a tliin membrane of ox-bladder de])rived of its 
outer muscular coating, at very nearly the same rate as 
when no membrane is interposed. 

Dutrochet was the first to study the phenomena of 
membrane diffusion. He took a glass funnel with a long 
and slender neck, tied a piece of bladder over the wide 
opening, inverted it, poured in brine until the funnel 
was filled to the neck, and immersed the bladder in a 



* From a Greek word meaning impulsion. 



394 



now CEOPS GROW 



vessel of water. Ho saw the liquid rise in tlie narrow 
tube and fall in the outer vessel. He designated the 
passage of water into the funnel as euclosmose, or inward 
propul&ion. At the same time he found the water sur- 
rounding the funnel to acquire the taste of salt. The 
outward transfer of salt was his exosmose. The more 
general word, Osmose, expresses both phenomena ; we 
may, however, employ Dutrochet's 
terms to designate the direction of 
osmose. 

Osmometer. — When the apparatus 
employed by Dutrochet is so con- 
structed that the diameter of the nar- 
row tube has a known relation to, is, 
for example, exactly one-tenth that of 
the membrane, and the narrow tube 
itself is provided with a millimeter 
scale, we have the Osmometer of Grah- 
am, Fig 67. The ascent or descent of 
the liqnit^in the tube gives a measure 
of the amount of osmose, provided the 
hydrostatic pressure is counterpoised 
l)y mahing the level of the liquid with- 
in and without equal, for which pur- 
poGc water is poured into or removed from the outer ves- 
sel. Graham designates the increase of volume in the 
osmometer as positive osmose, or simply osmose, and dis- 
tinguishes the fall of liquid in the narrow tube as nega- 
tive osmose. 

In tlie figure, the external vessel is intended for the reception of 
water. The funnel-shaped interior vessel is closed below with mem- 
brane, and stands upon a shelf of perforated zinc for support. The 
graduated tube fits the neck of the funnel by a ground joint. 

Action of the Membrane. — When an attraction exists 
the membrane itself and one or more of the substances 
between wdiich it is interposed, then the rate, amount, 
and even direction, of diffusion may be greatly changed. 




FJir. 07. 



CAUSES OF THE MOTION" OF JUICES. 395 

Water is imbibed by the membrane of bladder much 
more freely than alcohol ; on the other hand, a film of 
colladion (cellulose nitrate left from the evaporation of 
its solution in ether) is penetrated much more easily by 
alcohol than by water. If, now, these liquids be sepa- 
rated by bladder, the apparent flow will be towards the 
alcohol ; but if a membrane of collodion divide them, 
the more rapid motion will be into the water. 

When a vigorous chemical action is exerted upon the 
membrane by the liquid or the dissolved matters, osmose 
is greatly heightened. In experiments with a sejotum of 
porous earthenware (porcelain biscuit), Graham found 
that in case of neutral organic bodies, as sugar and alco- 
hol, or neutral salts, like the alkali-chlorides and nitrates, 
very little osmose is exhibited, i. e., the diffusion is not 
perceptibly greater than it would be in absence of the 
porous diaphragm. 

The acids, — oxalic, nitric, and hydrochloric, — mani- 
fest a sensible but still moderate osmose. Snlphuric 
and phosphoric acids, and salts having a decided alka- 
line or acid reaction, viz., acid potassium oxalate, sodi- 
um pliosphate, and carbonates of potassium and sodium, 
exhibit a still more vigorous osmose. For example, a 
solution of one part of potassium carbonate in 1,000 
parts of water gains volume rapidly, and to one part of 
the salt that passes into the water 500 parts of water 
enter the solution. 

In all cases where diffusion is greatly modified by a 
membrane, the membrane itself is strongly attacked and 
altered, or dissolved, by the liquids. When animal 
membrane is used, it constantly undergoes decomposi- 
tion and its osmotic action is exhaustible. In case 
earthenware is employed as a di;q")hragm, portions of its 
calcium and aluminium are always attacked and dis- 
solved by the solutions upon which it exerts osmose. 

Graham asserts that to induce osmose in bladder, the 



39G HOW CROP.S GROW. 

chemical actiun on the menibnuie must be different on 
tlie two sides, and ap2)arently not iji degree onlj^ but 
also in kind, viz., an alkaline action on the albuminoid 
substance of the membrane on the one side, and an acid 
action on the other. The water ap^^ears always to accu- 
mulate on the alkaline or basic side of the membrane. 
Hence, with an alkaline salt, like potassium carbonate, 
in the osmometer, and water outside, the flow is inwards ; 
but with an acid in the osmometer, there is negative 
osmose, or the flow is outwards, the liquid then falling 
in the tube. 

Osmotic activity is most highly manifested in such 
salts as easily admit of decomposition with the setting 
free of a part of their acid, or alkali. 

Hj^dration of the membrane. — It is remarkable 
that the rapid osmose of potassium carbonate and other 
alkali-salts is greatly interfered with by common salt, is, 
in fact, reduced to almost nothing by an equal quantity 
of this substance. In this case it is j^robable that the 
physical effect of the salt, in diminishing the powder of 
the membrane to imbibe water (p. 393), operates in a 
sense inverse to, and neutralizes the chemical action of, 
the carbonate. In fact, the osmose of the carbonate, as 
well as of all other salts, acid or alkaline, may be due to 
their effect in modifying the luidrailon,'^' or power of the 
membrane, to imbibe the liquid, which is the vehicle of 
their motion. Graham suggests this view as an explana- 
tion of the osmotic influence of colloid membranes, and 
it is not unlikely that in case of earthenware, the chem- 
ical action may exert its effect indirectly, viz., by pro- 
ducing hydrated silicates from the burned clay, which 
are trulv colloid and analojrous to animal membranes in 
respect of imbibition. Graham has shown a connection 
between the hydrating effect of acids and alkalies on 
colloid membranes and their osmotic rate. 



*In case irafcr is onii^loyi^il as the Hqiiicl. 



CAUSES OF THE MOTION OF JUICES. 



397 



*'It is well known that fibrin, albumin, and animal 
membrane swell much more in very dilute acids and 
alkalies than in pure water. On the other hand, when 
the proportion of acid or alkali is carried beyond a point 
peculiar to each substance, contraction of the colloid 
takes place. The colloids just named acquire the power 
of combining with an increased proportion of water 
and of forming higher gelatinous hydrates in conse- 
quence of contact with dilute acid or alkaline reagents. 
Even parchment-paper is more elongated in an alkaline 
solution than in pure water. When thus hydrated 
and dilated, the colloids present an extreme osmotic 
sensibility." 

An illustration of membrane-diUiision which is highly 
instructive and easy to produce, is the following : 

A cavity is scooped out in a carrot, as in Fig. G8, so 
that the sides remain J inch or so thick, 
and a quantity of dry, crushed sugar is 
introduced ; after some time, the previ- 
ously dry sugar will be converted into a 
syrup by withdrawing water from the flesh 
of the carrot. At tlie came time the latter 
will visibly shrink from the loss of a ])or- 
tion of its liquid contents. In this case 
the small j^ortions of juice moistening the 
cavity form a strong solution with the sugar in contact 
w^ith them, into which water diffuses from the adjoining 
colls. Doubtless, also, sugar penetrates the pairenchyma 
of the carrot. 

In the same manner, sugar, when sprinkled over thin- 
skinned fruits, shortly forms a syrnp with the water 
which it thus withdraws from them, and salt jmcked 
with fresh meat runs to brine by tlie exosmose of the 
juices of the flesh. In these cases the fruit and the 
meat shrink as a result of the loss of water. 

Graham observed gum tragacanth, which is insoluble 




Fiff. G8. 



308 HOW CROPS GROW. 

in water, to cause a rapid passage of water tlirongli a 
membrane in the same manner from its power of imbibi- 
tion, although here there could be no exosmose or out- 
ward movement. 

The application of these facts and principles to explain- 
ing the movements of the liquids of the plant is obvious. 
The cells and the tissues com^oosed of cells furnish pre- 
cisely the conditions for the manifestation of motion by 
the imbibition of liquids and by simple diffusion, as well 
as by osmose. The disturbances needful to maintain 
motion are to be found in the chemical changes that 
accompany tlie processes of nutrition. The substances 
that normally exist in the vegetable cells are numerous, 
and they suffer remarkable transformations, both in 
cliemical constitution and in physical properties. The 
rapidly-diffusible salts that are presented to the plant by 
the soil, and the equally diffusible sugar and organic 
acids that are generated in the leaf-cells, are, in part, 
converted into the sluggish, soluble colloids, soluble 
starch, dextrin, albumin, etc., or are deposited as solid 
matters in the colls or upon their walls. Thus the dif- 
fusible contents of the plant not only, but the mem- 
branes which occasion and direct osmose, are subject to 
perpetual alterations in their nature. More than this, 
the plant grows ; new cells, new membranes, new pro- 
portions ot* soluble and diffusible matters, are unceas- 
ingly brought into existence. ImhihUioii in the cell- 
membranes and their solid, colloid contents, Diffusion 
in the liquid contents of the individual cells, and Osmose 
between the liquids and dissolved matters and the mem- 
branes, or colloid contents of the cells, must unavoid- 
ably take place. 

That we cannot follow the details of these kinds of 
action in the plant does not invalidate the fact of their 
operation. The plant is so complicated and presents 
such a number and variety of changes in its growth. 



CAUSES OF THE MOTION^ OF JUICES. 399 

that we can never expect to understanrl all its mysteries. 
From what has been briefly explained, we can compre- 
hend some of the more striking or obvious movements 
that proceed in the vegetable organism. 

Absorption and Osmose in Germination. — The 
absorption of water by the seed is the first stejo in Ger- 
mination. The coats of the dry seed, when put into the 
moist soil, imbibe this liquid which follows the cell- walls, 
from cell to cell, until these membranes are saturated 
and swollen. At the same time these membranes occa- 
sion or permit osmose into the cell-cavities, which, dry 
before, become distended with liquid. The soluble con- 
tents of the cells, or the soluble results of the transforma- 
tion of their organized matters, diffuse from cell to cell 
in their passage to the expanding embryo. 

The quantity of water imbibed by the air-dry seed commonly 
amounts to 50 and may exceed 100 per cent. R. Hoffmann has made 
observations on this subject (Ts. »S^<., VII, p. 50). The absorption was 
usually complete in 48 or 72 hours, and was as follows in case of certain 
agricultural plants: — 

Per cent. Per cent. 



Mustard 8.0 

Millet 25.0 

Maize 44.0 

AVheat 45.5 

Buckwheat 46.8 

Barley 48.2 

Turnip 51.0 

Rye 57.7 



Oats 59.8 

Hemp GO.O 

Kidney Bean 5)0.1 

Horse Bean 104.0 

Pea .100.8 

Clover 117.5 

Beet , 120.5 

White Clover 12G.7 



Root-Action. — Absorption at the roots is unquestion- 
ably an osmotic action exercised by the membrane that 
bounds the young rootlets and root-hairs externally. In 
principle it does not differ from the absor2)tion of water 
by the seed. The mode in which it occasions the sur- 
prising phenomena of bleeding or rapid flow of sap from 
a wound on the trunk or larger roots is doubtless essen- 
tially as Hofmcister first elucidated by experiment. 

This flo2v proceeds in the ducts and wood -ceils. 
Between these and the soil intervenes loose ccU-tissue 



400 



now CROPS GROW. 



surrounded by a compiicter epidermis. Osmose takes 
place in the epidermis witii such energy as not only to 
distend to its utmost the cell-tissue, but to cause the 
water of the cells to filter tlirougli their walls, and thus 
gain access to the ducts. The latter are formed in young 
cambial tissue, and, when new, are very delicate in their 
walls. 

Fig. G9 represents a simple apparatus by Sachs for 
imitating the supposed mechanism and process of Root- 
action. In the Fig., g g represents a short, wide, open 
glass tube ; at a, the tube is tied over and se- 
curely closed by a piece of pig's bladder ; it is then 
filled with solution of sugar, and the other end, 
h, is closed in similar manner by a piece of 2:)arch- 
ment-papor (p. 59). Finally a cap of India-rub- 
ber, K, into whose neck a narrow, bent glass 
tube, r, is fixed, is tied on over 1). (These join- 
ings must be made very carefully and firmly.) 
The space within r A' is left empty of liquid, and 
the combination is placed in a vessel of water, as 
in the figure. C represents a root-ceU whose 

exterior wall (cuticle), 
a, is less penetrable 
under pressure than its 
interior, 1) ; r corres- 
ponds to a duct of vas- 
cular tissue, and the 
s u r r u n d i n g w ate r 
takes the place of thnt 
existing in the pores of 
the soil. The water shortly penetrates the cell, C, dis- 
tends the previously flabby membranes, under the accu- 
mulating tension filters through b into r, and rises in 
the tube ; where in Sachs's experiment it attained a 
hei2:ht of 4 or 5 inches in 24 to 48 hours, the tube, r, 
being about 5 millimeters wide and the area of b, 700 sq. 




Fio-. G9. 



CAUSES OP THE MOTION OF JUICES. 401 

mm. Wlicn we consider tho vast root-surface exposed 
to the soil, in case of a vine, and that m^yriads of root- 
lets and root-hairs unite their action in the compara- 
tively nnrrow stem, we must admit that the a])paratus 
above figured gives us a very satisfactory glance into the 
causes of bleeding. 

Motion of Nutritive or Dissolved Matters; Se- 
lective Power of the Plant. — The motion of the sub- 
stances that enter the plant from the soil in a state of 
solution, and of those organized within the plant is, to a 
great degree, separate from and independent of that 
which the water itself takes. At the same time that 
water is passing upwards through the plant to make 
good the waste by evaporation from the foliage, sugar or 
otlier carbhydrate generated in tlie leaves is diif using 
against the water, and linding its way down to the very 
root-tips. This diffusion takes place mostly in the cell- 
tissue, and is undonl^tedly greatly aided by osmose, i. e., 
by the action of tlie membranes themselves. The very 
thickening of the cell-walls by the deposition of cellulose 
would indicate an attraction for the material from which 
celluJose is organized. The same transfer goes on sim- 
ultaneously in all directions, not only into roots and 
stem, but into tlie new buds, into flowers and fruit. 
We have considered the tendency to equalization between 
two masses of liquid separated from eacli other by pen- 
etrable membranes. This tendency makes valid for the 
organism of the plant the law that demand creates snp- 
j^ly. In two contiguous cells, one of wdiich contains 
solution of sugar, and the other solution of potassium 
nitrate, tliese substances must diffuse until they are 
mingled equally, unless, indeed, the membranes or some 
otli or substance present exerts an opposing and prepon- 
derating attraction. 

In the simplest phnses of diffusion each snbstance is, 
to a certain degree, independent of every other. Any 
2G 



402 now CROPS GROW. 

salt dissolved in the water of the soil must diffuse into 
the root-cells of a plant, if it be absent from the sap of 
this root-cell and the membrane ^lermit its j^assage. 
When the root-cell has acquired a certain proportion of 
the salt, a proportion equal to that in the soil-water, 
more cannot enter it. So soon as a molecule of the salt 
has gone on into another cell or been removed from the 
sap by any chemical transformation, then a molecule 
may and must enter from without. 

Silica is much more abundant in grasses and cereals 
than in leguminous plants. In the former it exists to 
the extent of about 25 parts in 1,000 of the air-dry foli- 
age, while the leaves and stems of the latter contain but 
3 parts. When these crops grow side by side, their 
roots are equally bathed by the same soil-water. Silica 
enters both alike, and, so far as regards itself, brings 
the cell-contents to the same state of saturation that 
exists in the soil. The cereals are able to dispose of 
silica by giving it a j^lace in the cuticular cells ; the 
leguminous crops, on the other hand, cannot remove it 
from their 'juices ; the latter remain saturated, and thus 
further diffusion of silica from without becomes impos- 
sible except as room is made by new growth. It is in 
this way that we have a rational and adequate explana- 
tion of the selective power of the plant, as manifested 
in its deportment towards the medium that invests its 
roots. The same principles govern the transfer of mat- 
ters from cell to cell, or from organ to organ, within the 
plant. Wherever there is unlike composition of two 
miscible juices, diffusion is thereby set up, and proceeds 
as long as the cause of disturbance lasts, provided im- 
penetrable membranes do not intervene. The rapid 
movement of water goes on because there is great loss of 
this liquid ; the slow motion of silica is a consequence 
of the little use that arises for it in the plant. 

Strong chemical affinities may be overcome by help of 



CAUSES OF THE MOTION" OF JUICES. 403 

osmose. Graham long ago observed the decomposition 
of alum (sulphate of aluminium and potassium) by mere 
diffusion ; its potassium sulphate having a higher diffu- 
sive rate than its aluminium sulphate. In the same 
manner acid potassium sulphate, put in contact Avith 
water, separates into neutral potassium sulphate and 
free sulphuric acid.* 

We have seen (pp. 170-1) that the plant, when veg- 
etating in solutions of salts, is able to decompose them. 
It separates the components of potassium nitrate — appro- 
priating the acid and leaving the base to accumulate in 
the liquid. It resolves chloride of ammonium, — taking 
up ammonia and rejecting the hydrochloric acid. The 
action in these cases we cannot definitely explain, but 
our analogies leave no doubt as to the general nature of 
the agencies that cooperate to such results. 

The albuminoids in their usual form are colloid 
bodies, and very slow of diffusion through liquids. 
They pass a collodion membrane somewhat (Schu- 
macher), but can scarcely penetrate parchment-paper 
(Graham). In the plant they are found chiefiy in the 
sieve-cells and adjoining parts of the cambium. Since 
for their production they must ordinarily require the 
concourse of a carbhydrate and a nitrate, they are not 
unlikely generated in the cambium itself, for here tlie 
descending carbhydrates from the foliage come in con- 
tact with the nitrates as they rise from the soil. On the 
other hand, the albuminoids become more diffusible in 
some of their combinations. Schumacher asserts that 
carbonates and i^hospliates of the alkalies considerably 
increase the osmose of albumin tlirough collodion mem- 
branes (Physih (lev Pflanzen, p. 128). It is probable that 
those combinations or modifications of the albuminoids 



*The cler'omposition of" these salts is begun by the Avater in AA^hieh 
they are dissolved, and is carried on by osmose, because the latter 
Beciu'es separation of the reacting substances. 



404 HOW CROPS GROW. 

which occur in the soluble cryst:illoids of aleurone 
(p. 105) and haemoglobin (p. 9?) are highly diffusible, 
as certainly is the case with the pqitones. 

Gaseous bodies, especially tlie carl)onic acid and oxy- 
gen of the atmosphere, which liave free access to the 
intercellular cavities of the foliage, and which are for the 
most part the only contents of the larger ducts, may be 
distributed throughout the plant by osmose after having 
been dissolved in the sap or otherwise absorbed by the 
cell-contents. 

Influence of the Membranes. — The sharp separa- 
tion of unlike juices and soluble matters in the plant 
indicates the existence of a remarkable variety and range 
of adhesive attractions. In orange-colored flowers we 
see upon microscopic examination that this tint is pro- 
duced by the united effect of yellow and red pigments 
which are contained in the cells of the petals. One cell 
is filled with yellow pigment, and the adjoining one with 
red, but these two colors are never contained in the 
same cell. In fruits we have coloring matters of great 
tinctorial power and freely soluble in water, but they 
never forsake tlie cells where they appear, never wander 
into the contiguous parts of the ])lant. In the stems 
and leaves of the dandeli(m, lettuce, and many other 
plants, a white, milky, and bitter juice is contained, but 
it is strictly confined to certain special channels and 
never visibly passes beyond them. The loosely disposed 
cells of the interior of leaves contain grains of chloro- 
phyl, but this substance does not appear in the epidermal 
cells, those of the stomata exce])ted. Sachs found that 
solution of indigo cpiickly entered the roots of a seedling 
bean, but required a considerable time to penetrate the 
stem. Hallier, in his experiments on the absorption of 
colored liquids Iw plants, noticed, in all cases when 
leaves or green stems were immersed in solution of indigo, 
or black-cherr}^ juice, that these dyes readily 2:)assed into 



CAUSES OF THE MOTIOIT OF JUICES. 405 

and colored the epidermis, the vascular and cambial tis- 
sue, and the parencliyma of the leaf-veins, keeping 
strictly to the cell-walls, but in no instance coniniuni- 
cated any color to the cells containing c]iloroi)hyl. 
{Phytojjathologie, Leipzig, 18G8, \). G7.) We must infer 
that the coloring matters either cannot penetrate the 
cells that are occupied with chloroj^liyl, or else are chem- 
ically transformed into colorless substances on entering 
them. 

Sachs has shown in numerous instances that the juices 
of the sieve-cells and cambial tissue are alkaline, while 
those of the adjoining cell-tissue are acid when examined 
by test-paper. {Exp. Phys. der Pflanzen, p. 394.) 

When young and active cells are moistened with solu- 
tion of iodine, this substance penetrates the cellulose 
witliout producing visible changa, Imt when it acts upon 
the protoplasm, the latter separates from the outer cell- 
wall and collapses towards the center of the cavity, as if 
its contents passed out, without a corresponding endos- 
mose being possible (p. 224). 

We may conclude from these facts that the membranes 
of the cells are capable of effecting and maintaining the 
separation of substances which have considerable attrac- 
tions for each other, and obviously accomplish this result 
by exerting their superior attractive or repulsive force. 

The influence of the membrane must vary in character 
with those alterations in its chemical and structural con- 
stitution which result from growth or any other cause. 
It is thus, in part, that the assimilation of external food 
by the plant is directed, now more to one class of 
proximate ingredients, as the carbhydrates, and now to 
another, as the albuminoids, although the supplies of 
food presented are uniform both in total and relative 
quantity. 

If a slice of red-beet be washed and put into water, 
the pigment which gives it color does not readily dissolve 



406 HOW CROPS GEUW. 

and diffuse out of the cells, but the water remains color- 
less for several days. The pigment is, however, soluble 
in water, as is seen at once by crushing the beet, where- 
by the cells are forcibl}^ broken open and their contents 
displaced. The cell-membranes of the uninjured root 
are thus apparently able to withstand the solvent power 
of water upon the pigment and to restrain the latter 
from diffusive motion. Upon subjecting the slice of 
beet to cold until it is thoroughly frozen, and then plac- 
ing it in warm water so that it quickly thaws, the latter 
is immediately and deei3ly tinged Avith red. The sudden 
thawing of the water within the pores of the cell-mem- 
brane has in fact so altered them, that they can no 
longer prevent the diffusive tendency of the pigment. 
(Sachs.) 



4. 



MECHANICAL EFFECTS OF OSMOSE ON THE PLANT. 

The osmose of water from without into the cells of the 
plant, whether occurring on the root-surface, in ths 
buds, or at any intermediate point where chemical 
changes are going on, cannot fail to exercise a great me- 
chanical influence on the phenomena of growth. Root- 
action, for example, being, as we have seen, often suffi- 
cient to overcome a considerable hydrostatic pressure, 
might naturally be expected to accelerate the develop- 
ment of buds and young foliage, especially since, as com- 
mon observation shows, it operates in perennial plants, 
as the maple and grape-vine, most energetically at the 
season when the issue of foliage takes place. Experi- 
ment demonstrates this to be the fact. 

If a twig be cut from a tree in winter and be placed in a 
room having a summer temperature, the buds, before dor- 



MECHANICAL EFFECT OF OSMOSE ON^ PLANTS. 407 



Y/!*'^. 



m 



^^i 



mant, shortly exhibit signs of growth, 
iiud if the cut end be immersed in wa- 
ter, the buds will enlarge quite after 
the normal manner, as long as the nu- 
trient matters of the twig last, or until 
the tissues at the cut begin to decay. 
It is the summer temi:>erature which 
excites the chemical clianges that re- 
sult in growth. Water is needful to 
occupy the expanding and new-form- 
ing cells, and to be the vehicle for the 
translocation of nutrient matters from 
the wood to the buds. Water enters 
the cut stem by imbibition or capillar- 
ity, not merely enough to replace loss 
by exhalation, but is also sucked in by 
osmose acting in the growing cells. 
Under the same conditions as to tem- 
l^erature, the twigs which are connected 
with active roots expand earlier and 
more rapidly than cuttings. Artificial 
pressure on the water which is pre- 
sented to the latter acts with an effect 
similar to that which the natural stress 
caused by the root-power exerts. This 
fact was demonstrated l)y Bochm 
{iSitzunyshcriclUe der Wiener AkcuL, 
18G3), in an experiment wliicli may be 
made as illustrated by the cut, Fig. 70. 
A twig with" buds is secured by means 
of a perforated cork into one end of a 
short, wide glass tube, which is closed 
below by another cork through which 
passes a narrow syphon-tube, B. The 
cut end of the twig is immersed in 
water, ir, which is put under j^ressure 
by pouring mercury into the upper 



408 HOW CU'JPo GROW. 

extremity of the syplion-tnbe. Horsc-cliestimt and grape 
twigs cut in February mid March jind llius treated — tlie 
pressure of mercury being ecpial to six to eight inches 
above tlie level, M — after four to six weeks, unfolded 
their buds with normal vigor, Avhile twigs similarly cir- 
cnmstanced but without pressure opened four to eight 
days later and with less appearance of strength. 

Fr. Schulz {Karsten's Bat. Untcrs., Berlin, II, 143) 
found that cuttings of twigs in the leaf, from the horse- 
chestnut, locust, willow and rose, subjected to hydro- 
static pressure in the same way, remained longer turges- 
cent and advanced much further in development of 
leaves and flowers than twigs simply immersed in water. 

'J'he amount of water in the soil influences both the 
absolute and lelative quantity of this ingredient in the 
plant. It is a common observation that rainy spring 
weather causes a rank growth of grass and straw, vrhile 
the yield of hay and grain is not correspondingly in- 
creased. The root-action must operate with greater 
effect, other things being equal, in a nearly saturated 
soil than in one which is less moist, and the young cells 
of a plant situated in the former must be sul)jected to 
greater internal stress than those of one growing in the 
latter — must, as a consequence, attain greater dimen- 
si<ms. It is not uncommon to find fleshy roots, espec- 
ially radishes which have grown in hot-beds, split apart 
lengthwise, and liallier mentions the fact of a sound 
root of petc^rsilia splitting o])en after immersion in water 
for two or three days. {Phytopathologie, \). 87.) This 
mechanical elfect is indeed commonly conjoined with 
others resulting from abundant nutrition, but increased 
bulk of a plant without corresponding increase of dry 
matter is doubtless in great part the consequence of large 
supplies of water to the roots and its vigorous osmose 
into the expanding plant. 



APPENDIX. 



CoMrosiTio^i OF VAiMOUS AGRICULTURAL PRODUCTS givins the Aver- 
age quantities uf Water, Nitrogen, Asli, and Asli-ingredients in 
1,000 parts of fresli or air-dry substances. Aeeording to Frof. E. 
von Wolff, 1880. 















cj 




a; 










cc 


f-l 


fac 




<— " 








0) 


o 




ci 


cS 


o 


l-H 


-M 










cfl 


w( 


+j 


r— < 


-** 


>^ 


^ 


o3 


^ 


i^ 


< 


Sh 


a2 


2 


^ 



O'c; '^1 



9 o ^< 



grassp:s. 

Rich pasture grass, 

Young grass and after- 
math, 

Orciiard grass, 

Ilye grass, 

Tiniotliy, 

CLOVERS AND LEGUMES. 

Red clover, young, 

Red clover in bud, 

Red clover in llower,. .. 
Lucern or Alfalfa, in 

early bloom, 

Alsike clover, 

AVhite clover in llower, 

ROOTS, TUBERS, IJULIiS. 

l?eets, 

Carrots, 

Rutabagas, 

Turnips, 

Sugar-beets, 

Radish, 

I'arsnip, 

Horseradish, 

Onion, 

Artichoke, HeliantJiXis,. 

Potato 

" vp:getap.les." 
C a b b a g e, loose outer 

leaves, 

Cabbage, heart, 

Caid itlower, heax't, 

Cucumber, fruit, 

Lettuce, 

Asparagus, sprouts, 

Spinage, . 

Musltroomn, edible, 

seeds OF cereals. 

Oats, 

Millet, 

Maize, 



Sorg^ium, 

Spring Wlieat, . . 
Spring Barley, . . 

Spring Rve,." 

AVinter AVheat,.. 
Winter Karley,. 
Winter Rye,..'... 



782 

800 
700 
700 
700 

860 
820 

800 

740 

820 
805 

880 
850 
870 
320 
815 
!)33 
703 
7(;7 
800 
800 
750 



800 
900 
004 
05(> 
040 
933 
903 
888 



7.2 

5.6 

5.7 
5.4 

6.0 
5.3 
4.8 

7.2 
5.3 
5.6 

1.8 

2.2 
2.1 
1.8 
1.6 
1.9 
5.4 
4.3 
2.7 
3.2 
3.4 



2.4 

3.0 
4.0 
1.6 

3.2 
4.9 
4.7 



143 17.6 

140 •>\).^ 

144 IG.O 

140 

143 20.5 
143il6.0 
143J 

144 20.8 

145 16.0 
143 1 17.6 



21.1 

18.1 

17.8 
20.4 

20.5 

14.0 
14.7 
13.7 

19.2 

8.6 

14.3 

9.1 

8.2 
7.5 
6.4 
7.1 
4.9 
10.0 
10.7 
7.4 
9.8 
9.5 



15.6 
9.6 

8.0 
5.8 
8.1 
5.0 
16.0 
10.0 

26.7 
20.5 
12.4 
16.0 
18.3 
22.3 
18.0 
16.8 
17.0 
17.9 



5.3 
5.0 
7.1 
7.1 

5.1 
5.5 
4.4 

4.5 
2.4 
3.1 

4.8 
3.0 
3.5 
2.9 
3.8 
1.6 
5.4 
7.7 
2.5 
4.7 
5.8 



5.8 
4.3 
3.6 
2.4 
3.7 
1.2 
2.7 
5.1 

4.8 
3.3 
3.7 
3.3 

5.6 
4.7 
6.2 
5.2 
2.8 
5.8 



0.3 


2.6 


0.7 


2.5 


0.8 


1.1 


0.7 


1.5 


0.4 


1.7 


0.3 


3.9 


0.3 


4.5 


0.3 


4,8 


0.3 


8.5 


0.3 


2.9 


1.0 


4.3 


1.5 


0.3 


1:7 


0.9 


0.4 


0.9 


0.6 


0.7 


0.6 


0.4 


1.0 


0.7 


0.2 


1.1 


0.4 


2.0 


0.2 


1.6 


1.0 


0.3 


0.3 


0.3 


1.5 


2.8 


0.8 


1.2 


0.5 


0.5 


0.6 


0.4 


0.8 


0.5 


0.9 


0.6 


5.7 


1.9 


0.2 


0.1 


0.4 


1.0 


0.4 


0.2 


0.1 


0.3 


0.5 


0.2 


0.3 


0.5 


0.5 


0.6 


0.3 




0.3 


0.5 


0.7 


0.1 


0.3 


0.5 



1.2 


1.9 


1.2 


1.4 


0.5 


1.3 


0.4 


2.2 


0.7 


2.4 


1.3 


1.7 


1.6 


1.5 


1.5 


1.3 


0.9 


1.6 


1.1 


0.9 


1.4 


1.8 


0.4 


0.8 


0.4 


1.1 


0.3 


1.1 


0.2 


0.8 


0.6 


0.9 


0.2 


0.5 


0.6 


1.9 


0.4 


2.0 


0.3 


1.3 


0.3 


1.4 


0.5 


1.6 


0.6 


1.4 


0.4 


1.1 


0.3 


1.6 


0.2 


1.2 


0.2 


0.7 


0.2 


0.9 


1.0 


1.6 


0.3 


3.4 


1.9 


6.8 


2.8 


6.5 


1.9 


5.7 


2.4 


8.1 


2.2 


9.0 


2.0 


7.8 


2.2 


9.2 


2.0 


7.9 


2.1 


5.6 


2.0 


8.5 



0.7 

1.0 
0.5 

0.8 
0.6 

0.3 
0.4 
0.4 

1.1 
0.4 
1.1 

0.3 
0.5 
0.7 
0.7 
0.3 
0.3 
0.5 
4.9 
0.4 
0.6 
O.G 



2.4 
1.3 
1.0 
0.4 
0.3 
0.3 
1.1 
0.4 



4.1 

4.6 
5.9 
6.5 
6.6 

0.4 
0.4 
0.4 

1.8 
0.3 
0.6 

0.2 
0.2 
0.1 
0.1 
0.2 

0.2 
1.5 
0.7 
0.2 
0.2 



0.1 
0.1 

0.3 
0.5 
1.3 
0.5 
0.7 
0.1 



0.5 10.5 
0.1 15.6 
0.1 0.3 
I 1.2 
0.3 



0.2 
0.4 



0.1 
0.5 

0.2, 



0.2 
0.3 
4.9 
0.3 



2.1 

1.1 
1.3 
2.1 
1.1 

0.6 
0.5 
0.5 

0.6 
0.5 
0.6 

0.9 
0.4 
0.5 
0.3 
0.3 
0.5 
0.4 
0.3 
0.2 
0.4 
0.3 



1.3 
0.5 
0.3 
0.4 
0.4 
0.3 
1.0 
0.1 

0.3 
0.1 
0.2 

0.1 
0.2 

0.1 

0.1 



409 



410 



HOW CIlOP.i GROW. 



Composition of various Agricultural Troducts.— [Continued.'] 















c3 








CD 


p 




O 


c3 

O 

a:' 


3 


Sj3 




1^ 


0^ 



SEEDS OF LEGUMES AND 
CLOVERS. 

Horse bean, llcta, 

Garden bean, Phaseolus, 

Soy bean, 

Pea, 

Ked Clover, 

White Clover, 

oil SEEDS. 

Cotton, 

Hemp, 

Flax, 

Mustard, 

fruits. 

Apple, entire fruit, 

Pear, entire fruit, 

Cherry, entire fruit, 

Plum, entire fruit, 

Grape, entire fruit, 

HAY. 

Alpine hay 

Froui very younjj: grass, 
From youuf:? j^rass and 

af termatli, 

From cereals eut in 

bloom, 

English rye grass, 

Red Clover, young, 

Red Clover in biul, 

Red Clover in flower,.. 

Red Clover, ripe, 

White Clover in flower, 

Alsike Clover, 

Lucern (Alfalfa) early 

bloom, 

STRAW. 

Oat 

Barley, 

Maize, 

Spring Wheat, 

AVinter Wheat, 

Winter Rye, 

P>uckwheat, 

I'ea, 

CHAFF, ETC. 

Oat Chaff, 

Rve Chaff, 

Wheat Chaff, 

Corn Cobs, 

MISCELLANEOITS. 

Tobacco leaves, 

Tobacco stems, 

Flax stalks, 

Hemp stalks, 

Hoi)s, entire plant, 

Cottonseed Cake, 

Linseed Cake, 



145 
150 
100 
143 
150 
150 



122 
118 
130 

831 
831 
825 
838 
830 

150 

150 

IGO 

150 
143 
1G7 
1(55 
IGO 
150 
1C5 
160 

IGO 

143 
143 
150 
143 
143 
143 
160 
160 



40.8 
39.0 
53.4 
35.8 
30.5 



36.5 
26.1 
32.8 



0.6 
0.6 



31.0 
27.4 
28.3 
23.4 
38.3 
33.8 

33.8 
46.3 
32.6 
36.5 

2.2 

3.3 

I 3.9 

■ I 2.9 

1.7, 8.8 



18.5 
25.5 



16.3 
35.5 
24.5 
19.7 
12.5 
23.2 
24.0 



143 
143 
143 
140 

ISO 
180 
120 
108 
140 
112 
122 



5.6 
6.4 
4.8 
5.6 
4.8 
4.0 
13.0 
10.4 



29.7 
82.4 



19.1 76.0 



59.4 
58.2 
82.3 
G8.4 
57.6 
44.7 
61.1 
40.0 



23.0 62.0 



61.6 
45.9 
45.3 
38.1 
46.0 
38. 2 
51.7 
43.1 



6.4 71.2 

5.8 82.7 

7.2 92.0 

2.3 4.5 

34.8 140.7 

24.6 64.7 

I 31.1 

I 31.7 

25.0 72.9 

62.1 66.4 

47.2 51.3 



12.9 


0.3 1.5 


2.2 


12.1 


0.4 1.5 


2.1 


12.6 


0.3 1.7 


2.5 


10.1 


0.2 1.1 


1.9 


13.5 


0.4 2.5 


4.9 


12.3 


0.2 2.5 

1 


3.9 


10.9 


2.3 1.9 


5.6 


9.4 


0.4 10.9 


2.6 


10.0 


0.7 2.6 


4.7 


5.9 


2.0 7.0 


3.7 


0.8 


0.6 0.1 


0.2 


1.8 


0.3 0.3 


0.2 


2.0 


0.1 0.3 


0.2 


1.7 


1 0.3 


0.2 


5.0 


0.1 1.0 


0.4 


7.7 


0.4 7.1 


2.4 


31.6 


1.3 10.1 


4.6 


22.3 


3.0 10.4 


5.1 


19.3 


1.0 3.4 


1.7 


20.2 


2.0 4.3 


1.3 


29.7 


1.9 23.5 


7.6 


25.3 


1.4 20.7 


7.G 


18.6 


1.1 20.1 


6.3 


10.0 


1.4 15.8 


6.9 


13.1 


4.4 18.4 


5.8 


11.1 


1.2 13.6 


5.0 


14.G 


1.1 25.2 


3.1 


16.3 


2.0 4.3 


2.3 


10.7 


l.(; 3.3 


1.2 


1(;.4 


0.5 4.9 


2.6 


11.0 


1.0 2.6 


0.9 


6.3 


0.6 2.7 


1.1 


8.6 


0.7 3.1 


1.2 


24.2 


1.1 9.5 


1.9 


9.9 


1.8 15.9 


3.5 


4.5 


2.9 4.0 


1.5 


5.2 


0.3 3.5 


1.1 


8.4 


1.7 1.7 


1.2 


2.3 


0.1 0.2 

1 


0.2 


40.9 


4.5 50.7 


10.4 


28.2 


6.6 12.4 


0.5 


9.7 


2.5 6.9 


2.0 


5.5 


0.6 16.8 


2.1 


17.9 


1.9 19.7 


7.0 


1,5.8 


' 2.9 


10.1 


12.5 


0.8 4.3 


8.1 



12.1 
9.7 

10.4 
8.4 

14.5 

11.6 

10.5 
16.9 
13.5 
14.6 

0.3 
0.5 
0.6 
0.4 
1.4 

2.7 
7.4 

5.9 

5.6 
6.2 
10.0 
6.9 
6.6 
4.4 
7.8 
4.1 

5.3 

2.8 
1.9 
3.8 
2.0 
2.2 
2.5 
6.1 
3.5 

1.3 

5.6 
4.0 
0.2 

6.6 
9.2 
4.2 
2.1 
5.8 
30.5 
16.2 



1.1 


0.2 


1.1 0.2 


0.8 


0.8 0.2 


0.9 0.5 


1.6 0.8 


0.7! 0.1 


0.1' 5.5 


0.8 0.4 


1.8 0.9 


0.1 0.1 


0.2 0.1 


0.2 0.4 


0.1 0.1 


0.5 0.3 


1.4 7.2 


2.7,15.9 


4.1 19.4 


1.5 24.7 


2.3 18.5 


1.8| 2.5 


1.71 1.8 


1.9; 1.6 


1.4 3.0 


4.5 


2.7 


1.6 


1.6 


3.6 


5.9 


2.0 


28.8 


1.8'23.4 


2.4'13.1 


1.2,18.2 


1.1 31.0 


1.6 18.8 


2.7 


2.9 


2.7 


2.9 


3.5 


50.4 


0.1 C6.4 ! 




74.7 


0.1 


1.3 


8.5 


8.1 


2.2 


1.6 


2.0 


1.7 


0.6 


3.1 


2.9 13.3 : 


0.8( 5.5 


1.7 


6.4 1 



INDEX. 



Absorption by the root, 260, 269, 272 
Access of air to interior of 

riant, 313 

Ao-vitic Acid 76 

Acetamide, 115 

Acids, Definition of 81 

Acids, Test lor 82 

Acid elements, • 127 

Acid-proteids 99 

Adhesion, 9, 388 

Agrieultnre, Art of 1 

Agricultural iiroducts. Compo- 
sition in 1,000 parts, . . .409 
Agricultural Science, Scope of . 7 
Air-passages in plant, .... 313 

Air-roots, 273 

Akene, 331 

Albumin, 89 

Albuminates, 99 

Albuminoids, Characters and 

composition, ... 87, 104, 100 
Albuminoids in animal nutrit- 
ion, 108 

Albuminoids, Diffusion of . . .403 
Albuminoids in oat-i>lant, . . 234 
Albuminoids, Mutual relations 

of 107 

Alb'iminoids, Proportion of, in 
vegetable products, . . .114 

Albuniose, 101 

Alburnum, 305 

Aleurone, 110 

Alkali-earths, 81, 139 

Alkali-earths, Metals ot . . .139 

Alkali-nu'tals, 138 

Alkalies, 81, 138 

Alkali-pvoteids, 99 

Alkaloids, 120 

Allylsulphocyanatc, ..... 129 

Ahunina, 143 

Aluiuiuium, 143 

Alumiuium pliosphate, . . . .28 

Amides, 114, 118 

Amido-aeids, 114, 118 

Amidoacetic acid, 115 

Amidocaproic acid, 116 

Amido valeric acid, 116 

Amiduliii, 52 

Amines, 119 

Ammonium Carbonate, ... 33 
Amniouiuni Salts in plant, 82, 113 
Amylan, . . . • 62 

411 



Amyloid, 43 

Amylodextrin, 53 

Amyloses, 39,40 

Anhydrous phosphoric acid, . 132 
Anhydrous sulphuric acid, . .130 

Anther, 318 

Apatite, 148 

Arabic acid, 58 

Arabin, 58 

Arabinose, 65 

Arrow root, 48 

Arsenic in plants, . . . 137, 210 
Ash-ingredients, .... 126, 161 
Ash-ingredients, Excess of . . 201 
Ash-ingredients, Excess of, how 

disposed of, 203 

Ash-ingredients, Function of in 

plant, 210 

Ash-ingredients, State of, in 

plant, 207 

Ash of plants, 13, 126 

Ash of plants. Analyses, Tables 

of 164 

Ash of plants. Composition of, 

normal, 177 

Ash of plants. Composition of, 

variations in 151 

Ash, I'roportions of. Tables, . .152 

Asparagin, 11(> 

Assimilation, 3i)4 

Atmosphere, Offices of . . . ..■{67 

Atoms 30 

Atomic weight, 31 

Avenin, 120 

IJark, 291, 2!)7 

IJarium in plants, 210 

liases, Delinition of Si 

llast-cells, r.ast-tissue, 293, 295, 2;t7 
IJean, Leaf, Section of . . . .308 

liean. Seed, 334 

IJerry, 331 

Detain, 116 

r.iology, 10 

I>lee(iing of vine, .... 271,371 

l>lood-fibrin, 91 

Done-black, 15 

Boron, Boric acid, 210 

Buds, Structure of ..... 283 
Buds, Development under pres- 
sure, 406 

Bull)s, 289 

Butyrie acid, 76 



412 



HOW CROPS GROW. 



Caesium, Action on oat, , . .20!) 

Catfein, 117 

Calcium, 139, 214 

Calcium, carbonate, 145 

Calcium, hydroxide, .... 143 

Calcium, oxide, 139 

Calcium, i)liosphate, . . .28, 148 

Calcium, suli)liate, 146 

Callous, 382 

Calyx, 317 

Cambium 294, 295, 299 

Cane-sugar, 65 

Capillary attraction, .... 389 

Carbamide, 115 

Carbliydrates, 39 

Carbhydrates, Composition . . 72 
Carbliydrates, Transformations 

of 70 

Carbon, Proi)crties of .... 14 

Carbon in ash, 128 

Carbon dioxide, 128 

Carbonates, 128, 144 

Carbonate of lime, 145 

Carbonate of potash, 144 

Carbonate of soda, 144 

Carbonic acid, X9, 128 

Carbonic acid as food of plant, 328 
Carbonic acid in ash-analyses, 149 

Carboxyl, 75, 77 

Casein, 84 

Caseose, 101 

Cassava, 51 

Causes of motion of juices, . .385 

Cell-contents, 249 

Cell-multiplication, 252 

Cell, Structure of 245 

Cells, Forms of 247 

Cellular plants, 243 

Cellular tissue, 255 

Cellulose, 40 

Cellulose, Composition .... 44 
Cellulose, Estimation .... 45 

Cellulose nitrates, 43 

('idlulosc snli)ha1es, 43 

Cellulose, Test for 44 

Cellulose, (Miaul ity of, in plants, 4(5 

Chemical :i,fti nit y," 29 

Chemical allinity overcome by 

osmose, 403 

Chemical combination, ... 29 
Chemical tleconiposition, ... 30 

Cliemistry, 10 

Clilorides 133,149 

Chloride of ammouiuu), decom- 

l>osed V)y plant, 184 

Chlorine, 132 

Chlorine essential to crops ? . .194 
Chlorine, function in ])lant, . 218 
Chlorine in strand plants, . .191 

Chlorophyl, 124, 307, 308 

Chlorophyl requires iron, . . 220 

Chlorophyllan, 125 

Choline 119 

Circulation of sap, . . „ . . .369 

Citric acid, 80 

Citrates, 80, 149 

Classes of plants, ...... 329 

Classification botanical, . , .329 



Clover, washed by rain, . . . 204 

Colloids, 392 

Conglutin, 95, 97 

Combustion, 18 

Composite plants, 330 

Concentration of i>lant-food, .185 
Concretions in plant, .... 205 

Coniferous plants, 330 

Copper in plants, 210 

Cork, 298 

Corm, 288 

Corolla 317 

Cotyledon, 290, 333 

Coniferous plants, 330 

Cryptogams, 315, 329 

Crystalloid aleurone, . . . .111 

Crystalloids, 392 

Crvstals in plant, 206 

Culms, 284 

Cyanides, 127, 129 

Cyanogen, 129 

Definite proportions, Law of . . 30 

Density of seeds, 339 

Depth of sowing, 355 

Dextrin, 53 

Dextrose, 63 

Diastase, ...... 67, 103, 360 

DilTusion of liquids, , . . , .390 

Diau'ious jilants, 318 

Drains stopiied by roots, . . .276 

Drupe, .331 

Dry weather, Etiect of, on 

plants, 157 

Ducts, 255,294 

Dulcite, 74 

Dundonald's treatise on Agri- 
cultural Chemistry, ... 4 

Elements of Matter, 8 

Embryo, 3.33 

Endogens 259, 290, .3.34 

Endosmose, 394 

Endosperm, 332 

Enzymes, 103 

Epidermis, 291 

p]pidermis of leaf, 308 

Eremacjiusis, 20. 

Excretions from roots, .... 280 
Exhalation of water from foli- 
age, 309 

Exogens, .... 239, 293, 296, 334 

Exosmose, 394 

Exudation of ash-ingredients, 203 
Eyes of potato, ....... 280 

Families, .328 

Fatty acids, 75 

Fats, 8.3 

Fats converted into starch, . . S-'S 

Fat in oat crop, 230 

Fat in Vegetable Froducts, . . 87 

Ferments, 102 

Ferric oxide, 142 

Ferric hydroxide, 1^2 

Ferric salts 142 

Ferrous oxide, ...... .1^1 

Ferrous hydroxide, 141 

Ferrous salts, 142 

Fertilization, 319 

Fibrin, 91,96 



INDEX. 



413 



Fibrinoucn, 91, 96 

Flax tiber, Fig., 41, 248 

Flax seed luucilage, . . . 58,02 

Flesh librin, 9'-^ 

Flower, 317 

Flow of sap, 371 

Fluorine in plants, 209 

Foliage, Offiees of 314 

Food of Plant, 3(J6 

Forniative layer, 245 

Formulas, Chemical, . . .33, 73 

Fructification, 319 

Fructose, <^>3 

Fruit, 330 

Galactin, Gl 

(Jalaetose, 65 

Gases, how distributed through- 
out the plant, 404 

Gelatinous Silica, 136 

Geniis ; Genera, 328 

Germ, 333 

Germination, 349 

Germination, Conditions of . . 351 
Germination, Chemical Physi- 
ology of 357 

Girdling, 383 

Glauber's Salt, 146 

Gliadin, 92 

Globulin, 96 

Glucoses, 39, 63 

Glucosides, 69 

Glutamin, 116 

Gluten, 92 

Gluten-Casein, 93, 95 

Glycerin, 86 

Glycogen 56 

Glycocoll, 116 

Glycollic acid 77 

Gourd fruits, 331 

Grains 331 

Grape Sugar, 63 

Growth, 252 

Growth of roots, 256 

Gum, Amount of, In plants, . . 62 

Gum Arabic, 57 

Gum Tragacanth, 57 

(Jun Cotton, 43 

Gypsum, 147 

Hacmetin 110 

Hannoglobin, 109 

Hallett's pedigree Avheat, .158, 344 

Hybrid, Hybri<lizing 324 

Hydration" of membranes, . . 396 
Hydrochloric acid, .... 23, 133 

Hydrocyanic acid, 129 

Hydrogen, . 22,112 

Hydrogen chloride, ..... 23 
Hydrogen sidphide, ... 26, 129 

ImV)ibition, 380 

Imides, 117 

Inorganic matter, 12 

Internodes, 284 

Inulin, 55 

Invertin, 193 

Iodine in plants, .... 134, 210 
Iodine, Solution of ...... 44 

Iron, 141,192 

Iron, Function of .... - .219 



Isomerism, 73 

Juices of the Plant, 309 

Lactic Acid, 77 

Lactose, 68 

Latent buds, 285 

Latex, 304 

Layers, » • 286 

Lead in plants, 210 

Leaf pores, 309 

Leaves, Structure of . . . 306, 308 
Leaves, office in nutrition, . .328 

Lecithin, 122 

Legume, 332 

Legumin, 95 

Leguminous plants, ..... 332 

Leucin, 116 

Levulin, 56 

Levulose, 63 

Ligiun, 41 

Lime, 139 

Liquid Diffusion, 390 

Litliia, Lithium, in plants, . .209 
Lujianin, Lupinin, Lupinidin, 120 

Magnesia, 140 

Magnesium, 140, 215 

Magnesium hydroxide, . . . .141 

Magnesium oxide, 140 

Maize fibrin, 93 

Malates, . 149 

Malic acid, 79 

Malonic acid, 79 

Malt, Chemistry of 358 

Maltose, 67 

Manganese, 142, 193 

Mannite, 74 

Mannose, 65 

Margarin, 85 

Medullary rays, 299 

Membrane-diffusion, . . 393,397 
Membranes, Influence on mo- 
tion of juices, 404 

Metals, Metallic elements, . .138 

Metapectic acid, 59 

Metarabin, 59 

Milk ducts, 304 

Miilc Sugar, C8 

Molecules, Molecular Weights, 32 

Mona'cious phints, 319 

Motion caused by adhesion, . ..'389 

Mucedin 92,321 

Multiple Proportions, . . . .32 

Muriate of potash, 149 

Muriatic acid, . .133 

Myosin, 97, 98 

Nectar, Nectaries, 319 

Neiirin, 120 

Nicotin 120 

Niter, Nitrate of potassium, . . 149 
Nitrates in ]>lan1s, .... 113, 149 

Nitric Acid in plant, 113 

Nitrogen, Properties of . . . .20 

Nitrogen in ash, 127 

Nodes, 284 

Non-metals, 127 

Notation, Chemical 33 

Nuclein, 122 

Nucleus, . .300 

Nut, ........... 331 



414 



now CROPS GROW. 



Nutrient matters in plant, Mo- 
tion of \ . . 401 

Nutrition of seedling, . , . .357 

Nutrition of plant, 3G6 

Oat plant, Composition a n d 

growth of 223 

Oats, weight per bushel, . . .17G 
Oil in seeds, etc., ...... 83 

Oil of vitriol, 26, 130 

Oils, Properties of 83 

Oleic acid, 86 

(^lein, 85 

Orders, 328 

Organic mattei', 12 

Organism, Organs, 243 

Osjuose, 303 

Osmose, mechanical effects on 

plant, 406 

Osmometer, 334 

Ovaries, 318 

Ovules, 318 

Oxalates, 78, 141) 

Oxalic acid, 78 

Oxides, 19, 20 

Oxides of iron, described, . 19, 141 
Oxides of manganese, described 142 

Oxyf atty acids, 77 

Oxygen, Properties of .... 16 
Oxygen occurrence in ash, • .128 
Oxygen in Assimilation, . . . 364 
Oxygen in Germination, . . .353 

Palmitic acid, 86 

Palmitin, 85 

Paiiain, 104 

Parenchyma, 255 

Papilionaceous plants, . . . 330 

Pappus, .331 

Pararabin, 59 

Paraglobulin, 96, 99 

Paragalactin, 61 

Pectic acid, 74 

Pectin bodies, 58, 59, 74 

Pectosic acid, 74 

Pectose, 58, 61, 74 

Pedigree wheat, ..... 158, 344 

Pepsin, 104 

Peptones, loo 

Permeability of cells, .... 253 

Petals, 318 

IMianerogams, Phaenogams,316, 32:> 

Phloridzin 69 

Pliosphate of lime, 148 

Phosphate of soda, 148 

Phosphate of potash, .... 147 

Phosphates, 28, 132, 147 

Phosphates function in plants, 211 
Phosphates relation to albu- 
minoids, 221 

Phosphoric acid, 27, 132 

Phosphorite, 148 

Phosphorized substances, . . 122 

Phosphorus 27 

Phosphorus pentoxide, . . 27, 132 

Physics, .10 

Physiology, 10 

Piperin, 121 

Pistils, 318 

i'ith, . . . - . c . , . .297 



Pith rays, 299 

Plastic'Elements of Nutrition, 109 

Plumule, 33J 

Pollarding, 286 

Pollen, 318 

Polyf/oman convolvulus, Fertil- 
ization of, Fig., 295 

Pome, 331 

Porosity of vegetable tissues, .385 
Potato leaf, Pores of. Fig., . . 309 
Potato stem. Section of, "Fig., .304 
Potato tuber. Structure and Sec- 
tion of, Fig., 300 

Potash, 138, 144 

Potash lye, 139 

Potassium 138, 211 

Potassium carbonate, . . . .144 

Potassium Chloride, 149 

Potassium hydroxide, . . . .139 

Potassium oxide, 138 

Potassium phosiihate, . . . .147 

Potassium silicate, 134 

Potassium sulphate, «... .146 

Prosenchyma, 255 

Protagon, 123 

Proteoses, 100 

Protoplasm, 245 

Protein bodies, or Proteids, . . 87 
Proximate Pi'inciples, .... 37 

Quack grass, 287 

Quantitative relations among 
ingredients of j)lant, . . . 220 

Quartz, 134 

Quince seed mucilage, .... 62 

Radicle, 333 

Raflinose, 68 

Reproductive Organs, . . 243, 315 

Rhizome, 287 

Rind, 297 

Rock Crystal, 134 

Root-action, imitated, . . . .400 
Root-action, Osmose in . . . 399 

Root cap, 257 

Root distinguished from steni, 258 

Root excretions, 280 

Root hairs, 265 

Root, Seat of absorptive force 

in, 270, 399 

Rot)t stock, 2S7 

Rootlets, 2(10 

Roots, Growth of 25(> 

Roots contact with soil, . . . 266 
Roots troing down for water, . .276 
Roots,\Searcli of food by , . .263 
Roots, (^uxntity of .... . .263 

Rubidium action on oat, . . . 209 

Runners, , .286 

Saccharose, 60 

Sacch arose, A m o u n t of, in 

plants, 66 

Sago -51 

Saiicin, 69 

Salicornia 191 

Sal-soda, 145 

Salsola , .191 

Salts, Definition of ..... 81 
Salts, in ash of plants, , . .143 
Saltwort, .191 



INDEX. 



415 



Samphire, 1^1 

Blip, 3(ii) 

Sap, Acid and alkaline . . . -'^TS 

Sap ascending, 379, 384 

Sap desccndinij, 382 

Saj), Composition of .... . 370 

Sap of sunflower, 378 

Sap, Spring flow of . . . , . 370 

Sap wood, • • -305 

Saponification, 85 

Saxifrarja crustata, 206 

Seed, 332 

Seed vessel, 330 

Seed, Ancestry of 346 

Seeds, constancy of coinpositionl45 

Seeds, Density of 339 

Seeds, Weight of 340 

Seeds, Water imbibed by . . . 399 
Selective power of plant, . . .401 

Seminose, *"'5 

Sepals, 317 

Sieve-cells, 303 

Sieve-cells in pith, .... 343, 345 

Silica, 134 

Silica entrance into plant, . .402 
Silica, Function of, in plant, . 216 

Silica in ash, 197 

Silica in textile materials, . . 200 
Silica unessential to plants, . .197 

Sili<*ates, 134 

Silicate of potassium, . . . .134 

Silicic acids, 135 

Silicon, 134 

Silicon, Dioxide 134 

Silk of maize, 319 

Silver-grain, 299 

Sinajiin, 120 

Soaps, 93 

Sodium 139 

Sodium carbonate, 144 

Sodium essential to ag. plants? 186 

Sodium hydroxide, 139 

Sodium in strand and marine 

plants, • -1^1 

Sodium oxide, 139 

Sodium sulphate, 146 

Sodium, Variations of, in field- 
crops, , . . . 188 

Sodium Chloride, 149 

Soil. Offices of 368 

Solanin, 121 

Solution of starch in Germina- 
tion, 358, 3G1 

Soluble silica, 135 

Soluble starch, ....... 52 

Species, 326 

Spirits of salt, 133 

Spongioles, 257 

Spores, 316 

Sports, 327 

Stamens, 318 

Starch, amount In plants, , . 51 

Starch-cellulose, 50 

Starch estimation, 52 

Starch in wood, ..... 373, 376 
Starch, Properties of .... 47 

Starch, Test for 49 

Stearic acid, 86 



Stearin, 85 

Stem, Endogenous ..... 290 

Sti-m, Exogenous 296 

Stem, Struciture of 289 

Stems, 282 

Stigma, 318 

Slomata, 309 

Stool, 287 

Suckers, 287 

Sucroses, 39, 65 

Sugar, Estimation of 65 

Sugar, in cereals, C9 

Sugar in Sap, 377 

Sugar of milk, 68 

Sulphate of lime, 146 

Sulphate of potash, 146 

Sulphate of soda, 146 

Sulphates, 26, 131, 146 

Sulphates, Function of . . . .210 
Sulphates reduced by plant, . 208 

Sulphides, 26, 130 

Sulphide of potassium, . . . .130 

Sulphites, 129 

Sulphur, 25, 129 

Sulphur in oat, 208 

Sulphur dioxide, 25,130 

Sulphurcted hydrogen, . .2(!, 115 

Sulphurets, 26 

Sulphuric acid, 26, 130 

Sulphuric acid in oat, . . . .208 

Sulphuric oxide (S()^) 209 

Sul])hurtrioxide(S<)3), . . .25,1.30 

Sulphurous acid, 25, 129 

Symbols, Chemical 31 

Tao-foo, i>6 

Tapioca, 51 

Tap-roots, 259 

Tartaric acid, 80 

Tartrates, 80 

Tassels of maize, ..... .319 

Theobromin, 118 

Tillering, 287 

Titanic acid, 137 

Titanium, 137, 209 

Translocation of substances in 

plant, 237 

Trypsin, 104 

Tubers, 273, 288 

Tuscan hat- wheat, 158 

Tyrosin, 116 

Ultimate Composition of A^ege- 

table Matters, 13, 29 

Umbelliferous plants, .... 330 
Unripe seed, Plants from . . .338 

Urea, 115 

Valence, 35 

Varieties, 158,326,327 

Vascular bundle of maize 

stalk, 291,293 

Vascular-tissue, 255 

Vegetable acids, 75 

Vegetable albumin, 90 

Vegetable casein, 94 

Vegetable cell 243 

Vegetable fibrin, ...... 92 

Vegetable globulins, 97 

Vegetable mucilage,. .... 57 
Vegetable myosins, .,,..• 98 



41G 



now CROPS GROW. 



Vegetable parchment, .... 44 

Vegetable tissue, 24G 

Vegetative organs, 243 

Vernin, 118 

Vicin, 120 

Vitality of roots, . ..... .282 

Vitality of seeds, 335 

Vitellin, 96 

Water, Composition of .... 37 
Water, Estimation of .... 39 
Water, Formation of .... 24 
Water in air-dry plants ... o 39 
Water in fresh plants, .... 38 
AVater in vegetation. Free ... 39 
Water in vegetation, Hygro- 
scopic, ......... 39 



Water-oven, 38 

Water-culture, 181 

Water-glass, 135 

Water Roots, 273 

Wax, 83 

Wood, 41, 305 

Wood cells, „ . 293 

Wood cells of conifers, . . . .301 

Woody stems, 305 

Woody tissue 255 

Xylin, 61 

Xylose, 62 

Yeast, 103 

Zantbophyl, .125 

Zein, 93 

Zinc, . o . . . o , . . . .210 




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growers, giving a wide range of experience. The autiior of this 
book is a recognized authority on the subject. Cloth, 12mo. 1.5C 

White's Cranberry Culture. 

Contents: — Natural History.i-Hlstory of Cnltivation.— Choice of 
liocation. — Prei>aring llic Ground. — Planting (lie Vines. — Manage- 
ment of Meadows. — Flooding. — Enemies and Difiiculi.ies Overcomo. 
— Picking. — Keeping. — Profit and Loss.— Letters from Practical 
Growers. — Insects Injurious to the Cranberry. By Joseph J. White, 
a practical grower. Illustrated. Cloth, 12mo. New and revised 
edition. 1.25 

Fuller's Practical Forestey. 

A Treatise on the Propagation, Planting and Cultivation, with a 
descrii^tion and the botanical and i)roj)er names of ail tlie indigen- 
ous trees of the United States, both Evergreen and Df^ciduous, with 
Notes on a large number of the most valuable Exotic Species. By 
Andrew S. Fuller, author of "Grape Culturist," "Small Fruit Cul- 
turist," etc. 1,50 

Stewart's Irri§:ation for the Farm, Garden and Orchard. 

This work is offered to those American Farmers and other cultiva- 
tors of the soil who, from painful experience, can readily appre^ 
ciate the losses which result from the scarcity of water at critical 
periods. By Henry Stewart. Fully illustrated. Cloth, 12mo. 1,50 



Quinn's Money in the Garden. 



By P. T, Quinn. The author gives in a plain, practical style, in- 
structions on three distinct, although closely connected branches 
of gardening — the kitchen garden, market garden, and field culture, 
trom successful practical experience lor a term ol years. Illustra- 
if-ed. Cloth, i2mo. 1^ 



STANDARD BOOKS. 

Roe's Play and Profit in My Garden. 

By E. P. Roe. The autlior lakes us to liis garden on the rocky hlU' 
skies in the vicinity of West Point, and shows us how out of it, 
after four years' exijerience, lie evoked a profit of $;1,(K)0, and this 
wliile carrying on i)astorai and literary lal)or. It is very rarely 
that so much literary taste and skill are niated to so much agri- 
cultural experience and good sense. Clotli, 12mo. 1.50 

The New Onion Culture. 

By T. Greiner. This new work is written by one of our most sue- ' 
cessful agriculturists, and is full of new, original, and iiiglily valu 
able matter of material interest to every one who raises onions in 
the family garden, or by the acre for market. By the process here 
described a crop of 2000 bushels per acre can be as easily raised as 
500 or COO bushels in the old way. Paper, >2mo. .60 

The Dairyman's Manual. 

By Henry Stewart, author of "The Shepherd's Manual," "Irriga- 
tion," etc. A useful and practical work, by a writer who is well 
known as thoroughly familiar with the subject of which he writes. 
Cloth, 12mo. 2.00 

Allen's American Cattle. 

Their History, Breeding and Management. By Lewis F. Allen. 
This book will be considered indispensable by every breeder of 
livestock. The lai'ge experience of the author in improving the 
character of American herds adds to the weight of his observations 
and iias enabled hiiu to produce a woric which will at once make 
good his claims as a standard autiiority on the subject. New and 
revised edition. Illustrated. Cloth, 12mo. 2.50 

Profits in Poultry. 

Useful and ornamental Breeds and their Profitable Management. 
This excellent work contains the combined experience; of a num- 
ber of practical men in all departments of poultry raising. It is 
pi'ofusely illustrated and forms a unique and important addition 
to our poultry literature. Cloth, 12ino. 1.00 

The American Standard of Perfection. 

The recognized standard work on Poulti-y in this country, adopted 
by the Ameri(!an Poultry Association. It contains a complete de- 
scription of all the recognized varieties of fowls, including turkeys, 
ducks and geese; gives instructions to judges; glossary of technical 
terms and nomenclature. It contains 244 pages, handsomely 
bound in cloth, embellished with title in go'.c'' oi\ front cover. $1.00 



Stoddard's An Egg Farm. 



By H. II. Stoddard. The management of poultry in large numbers, 
being a series of articles written for the American Agricultur- 
ist. Illustrated. Cloth, l2mo, JSC 



STArrDAED BOOKS. 

Stewart's Shepherd's Manual, 

A V;ilii;il)le Priict ical Treatise on the Slieep for Ainorioan larmera 
and sheep growers. It is so ph.»u lliat. a taiiiici or a tanner's son 
wlio lias never kept a slieep, may learn from its images how to 
manage a Hock snceesst'uUy, and yet so complete that i-vcn the ex- 
perienced shepherd may gather many suggestions from It. The 
results of personal experience of some years with the characters 
of the various modern breeds of sheep, and the sheep raisinpj capa 
bilities of many portions of our extensive territory and that of 
Canada — and the careful study of the diseases to which our sheep 
are chietly subject, with those by which they may eventually be 
afflicted through ttnforseen accidetits — as well as the methods of 
management called fcr under our circumstances, are carefully 
described. By Henry Stewart. Illustrated. Cloth, 12mo. 1.50 

Wri§:ht's Practical Poultry-Keeper. 

Uy L. Wright. A complete and standard guide to the management 
of poultry, for domestic use, the markets or exhibition. It suits at 
once the plain poulterer, who must make the business pay, and the 
chicken fancier whose taste is for gay plumage and strange, brigltt 
birds. Illustrated. Cloth, 12mo. $!2.00 

Harris on the Pi§:. 

New Edition. Revised and enlarged by the author. The points of 
tlie various English and American breedsare thoroughly discussed, 
and the great advantage of using thoroughbred males clearly 
shown. Tiie work is equally valuable to the farmer who keeps but 
few pigs, and to the breeder on an extensive scale. By Joseph 
Harris. Illustrated. Cloth, 12mo. 1.50 

The Farmer's Veterinary Adviser. 

A guide to the Prevention and Treatment of Disease in Domestio 
Animals. This is one of the best works on this subject, and is es- 
])i'cially designed to supply the need of the busy American Farm 
er, wiio can rarely avail himself of the advice of a Scientific Voter 
inarian. It is brought up to date and treats of the Prevention ol 
Disease as well as of the Remedies. By Prof. Jas. Law. Cloth. 
Crown, 8vo. 3.00 

Dadd's American Cattle Doctor. 

By r.eorge II. Dadd, M. D.. Veterinary Practitioner. To help every 
man to bs liis own cattle-doctor; giving the necessary information, 
for preserving the health and curing the diseases of oxen, cows, 
sheep and swine, with a great variety of original recipes, and val- 
uable information on farm and dairy management. Cloth, 12mo. 1.50 

Cattle Breeding:. 

By Wm. Warfield. This work is t>y common consent the mos*; 
valuable and pre-eminently practical treatise on cattle-breeding 
ever i)nblished in America, being the actual experience and ob- 
servance of a practical man. Cloth, 12mo. y-00 



STAITDARD BOOKS, 

Dadd's American Cattle T^^^cton 

A complete work on all tli3 Diseases of Cattle, Slicep and Swine, In* 
cliulinj^ every Disease peculiar to America, and embracing all llie 
latest inlorniatioii on the Cattle Plague and Trichina; containing 
also a guide to symptoms, a table ot Weights and Measures, aiul a 
lisco'' Valuable JNIedicines. T.y George H. Dadd, V. S., twenty-five 
years -:. leading Veterinary Surgeon in England and the United 
States, and author of the "American lleiormed Horse Book," Cloth, 
octavo. Illustrated. 2.50 

Cattle and Their Diseases. 

By A. J. Murray, M. R. C. V. S. Breeding and Management of Cat- 
tle. This is one of the very lew works devoted exclusively to 
cattle diseases, and will be particularly vahiable to cattlemen 
for that reason. It is written in plain, simple language, easily un- 
derstood by any farmer, while it is learned and teciinical enough 
to satisfy any veterinary stirgeon. Cloth, 12mo. 2.00 

^iios, £nsila§:e, and Sila§:e. 

A practical Treatise on the Ensilage of Fodder Corn, containing 
the most recent and authentic information on this important sub- 
ject, by Manly Miles, M. D. F. R. M, S. Illustrated. Cloth, l2mo. .50 

Manures. 

How to Make and How to Use tliem. By Frank W. Sempers. ITi© 
author has made a concise, practical handbook containing the lat- 
est researches in agriculture in all parts of the world. The reports 
of the agricultural experiment stations have furnished many val- 
uable suggestions. Both coramercial and home-made manures 
are fully described, and many formulas for special crops and soils 
are given. Price j)ostpaid, pai)er 50 cents, clotli. 1.00 

Potato Pests. 

^'o farmer can afford to be without this lUtle book. It gives th9 
most complete account of the Colorado Beetle anywhere to be 
found, and includes all the latest tliscoveries as to the habits of the 
insect and the various means for its destrtiction. It is well illustra- 
ted, and exliibits in a map the spread or the insect since it left its 
native home. By Prot.C. V. Riley. Paper, .50 

four Plants. 

i'lain aiut Practical Directions for the Treatment of Tender and 
Hardy Plants in the House and in the Garden, iiy James Sheehan. 
The work meets the wants of the amateur who grows a tew plants 
in tlie wintlow, or has a small Hower garden, l^aper covers. .4C 

Pedder's Land-Measurer for Farmers. 

A convenient Pocket Companion, showing at once tho contents ot 
any piece of land, Avhen its length and width are unknown, up to 
1500 fe^t either way, with various other usetui tarui tables. Cloth, 
ISmo. ,66 



STA.NDAED BOOKS, 

flop Culture. 

Flain directions given by ten experienced cultivators. Revised, 
enlarged and edited by A. S. Fuller. Forty engravings. .30 

Wheat Culture. 

How to double the yield and increase the profits. By D. S. Curtiss, 
.Washington, D. C Importajice of llie Wheat Crop. Varieties Most 
Grown in the United States. Examples ot Successful Wheat Cul- 
ture. Illustrated. Paper covers. .50 

Starr's Farm Echoes. 

By F. Ratcliford Starr, Echo Farm, Litchfield, Ct. This handsome 
little book tells how the author turned from a successful business 
career to agricultural i^ursuits, and has achieved health, happiness 
and prosperity ui^on his broad acres near Litchfield. Cloth, 12mo. 
Illustrated. .50 

The American Merino. For Wool or tor Mutton. 

A practical and most valuable work on the selection, care, breeding 
and diseases of the Merino sheep, in all sections of the United 
States. It is a full and exhaustive treatise upon this one breed of 
sheep. By Stephen Powers. Cloth, 12mo. 1.50 

Coburn's Swine Husbandry. 

^ew, revised and enlarged edition. The Breeding, Rearing, and 
Management of Swine, and the Prevention and Treatment ot their 
Diseases. It is the fullest and freshest compendium relating to 
Swine Breeding yet offered. By F. D. Coburn. Cloth, 12mo. 1.75 

Tobacco Culture: Full Practical Details. 

This useful ano. "aluable work contains fulldetailsof every process 
from the Selection and Propagation of the Seed and Soil to the 
Harvesting, Curing and Marketing the Crop, with illustrative en- 
gravings of the operations. The work was prepared by Fourteen 
Expeiienced Tobacco Growers, residing in different parts of the 
country. It also contains notes on the Tobacco Worm, with Ulus- 
Ir at ions. 8vo. .25 

Keeping One Cow. 

A collection of j)rize Essays and Selections from a number of odier 
Essays, with editorial notes, suggestions, etc. This book gives tlie 
iatest infornialion, andiu a clear and condensed form, upon the 
management of a single iMilch Cow. Illustrated with full page en- 
gravings of the most famous dairy cows. Cloth, 12mo. 1.00 

Guenon's Treatise on Milch Cows. 

A treatise on the Bovine Species in General. An entirely new 
translation of the last edition of this popular and mstrucUve book. 
By Thomas J. Hand, Secretary of tlie American Jersey Cattle Club. 
With over 100 illustrations, especially engraved tor this work. 
Ciotn, l2mo. l-W 




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